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Blood, Vol. 91 No. 2 (January 15), 1998:
pp. 585-594
Circulating CD8 T Lymphocytes in Human Immunodeficiency
Virus-Infected Individuals Have Impaired Function and Downmodulate
CD3 , the Signaling Chain of the T-Cell Receptor Complex
By
Linda A. Trimble and
Judy Lieberman
From The Center for Blood Research, Harvard Medical School, Boston,
MA.
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ABSTRACT |
Although human immunodeficiency virus (HIV)-infected subjects
without acquired immunodeficiency syndrome have a high frequency of
HIV-specific CD8 T lymphocytes, freshly isolated lymphocytes frequently
lack detectable HIV-specific cytotoxicity. However, this effector
function becomes readily apparent after overnight culture. To
investigate reasons for T-cell dysfunction, we analyzed T-cell
expression of the cytolytic protease granzyme A and of CD3 , the
signaling component of the T-cell receptor complex. An increased
proportion of CD4 and CD8 T cells from HIV-infected donors contain
granzyme A, consistent with the known increased frequency of activated
T cells. In 28 HIV-infected donors with mild to advanced
immunodeficiency, a substantial fraction of circulating T cells
downmodulated CD3 (fraction of T cells expressing CD3, 0.74 ± 0.16 v 1.01 ± 0.07 in healthy donors; P < .0000005). CD3 expression is downregulated more severely in CD8 than
CD4 T cells, decreases early in infection, and correlates with
declining CD4 counts and disease stage. CD3 expression increases
over 6 to 16 hours of culture in an interleukin-2-dependent manner,
coincident with restoration of viral-specific cytotoxicity. Impaired
T-cell receptor signaling may help explain why HIV-specific cytotoxic T
lymphocytes fail to control HIV replication.
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INTRODUCTION |
IN HUMAN immunodeficiency virus
(HIV)-infected individuals who have not developed acquired
immunodeficiency syndrome (AIDS)-opportunistic infections, there is a
high frequency of circulating CD8+ T cells bearing T-cell
receptors (TcRs) that recognize HIV-infected cells.1 As
many as 1 in 100 circulating T cells may be capable of responding to a
particular HIV peptide.2,3 Despite the vigorous expansion
of antiviral CD8+ T cells, which can develop into effector
cells that lyse HIV-infected targets and secrete soluble factors that
suppress HIV replication, the cellular immune response is unable to
control viral production. It has been estimated that as many as 10 billion virions are produced each day, even in asymptomatic infected
individuals.4,5 The reasons for the failure of T-cell
function could be because of many factors, including the known paucity
of viral-specific CD4 helper cells that are important regulators of CD8
T-cell function, the state of chronic inflammation characteristic of
HIV infection, or immune dysfunction in the setting of antigen excess.
When freshly isolated peripheral blood mononuclear cells (PBMCs) from
HIV-infected donors are assayed for HIV-specific cytolytic activity,
laboratories have differed widely in their detection of viral-specific
cytotoxicity. Several early reports suggested that 80% to 90% of
HIV-infected donor PBMCs had HIV-specific cytotoxic T lymphocyte
(CTL) activity readily demonstrable above
background.6-8 In these studies the cytotoxicity assay time
ranged from 6 to 16 hours and the cut-off for positive activity was
less than what has become the standard of 10% above lysis of wild-type
vaccinia-infected cells. We found that in shorter cytotoxicity assays
(4-hour Cr release), high levels of specific cytotoxicity by fresh
PBMCs were uncommon but developed after in vitro culture in the
presence of mitogen and interleukin-2 (IL-2).9
Recently we found that viral-specific cytolytic activity develops after
overnight culture. This rapid increase in specific cytotoxicity,
typically from undetectable above background to 10% to 30%
HIV-specific cytotoxicity, as measured in a 4-hour 51Cr
release assay at an effector:target ratio of 25 to 50:1, could not be
explained by clonal expansion of viral-specific T cells in less than
one day. This suggested that the circulating viral-specific CD8+ T cells were either precursor CTLs, which had not
differentiated into mature effector CTLs containing cytotoxic granules,
or were functionally defective. Because of the high frequency of
activated circulating CD8 T cells10-12 and the high
likelihood of a prior encounter with HIV antigen, the first hypothesis
was unlikely and indeed proved not to be the case. Circulating CD8 and
CD4 T cells in HIV-infected subjects compared with healthy donors have
an unusually high percentage of cells containing cytolytic granules as
measured by intracellular staining for the most abundant granule serine
protease, granzyme A (grnA).
Cancer patients and tumor-bearing mice develop progressive
immunodeficiency, which resembles in some ways that of HIV-infected patients, including decreased delayed type hypersensitivity, decreased T-cell cytolytic activity, and impaired lymphokine and proliferative responses. Lymphocytes infiltrating solid tumors (TILs) of various types and circulating lymphocytes in Hodgkin's disease and B-cell lymphoma patients have a defect in signaling by the TcR linked to
abnormally low expression of CD3.13-16 This suggested
that a defect in CD3 expression might also occur in HIV-infected
subjects.
The first step in T-cell activation by antigen-presenting cells is
engagement of the TcR complex composed of a clonotypic dimeric TcR,
required for antigen recognition, in noncovalent association with CD3,
a multicomponent signal transduction complex. CD3 consists of CD3 ,
CD3 , and CD3 chains and a -chain-containing dimer, which may
be a homodimer or heterodimer with  or Fc receptor chain
(reviewed in Weiss and Littman17). The chain is also an
important signaling molecule in natural killer (NK) cells, which do not
express the TcR and other CD3 components. All components of the CD3
complex are required to transport the TcR to the T-cell surface,18 but the chain differs from the other
components in rapid cycling from the cell surface.19 CD3
is central to transmission of the TcR activation signal. Failure of
signal transduction should lead to failure of effector T-cell function,
including cytokine secretion and cytolysis.
In 28 HIV-infected donors with varying degrees of immunodeficiency, we
found significant downmodulation of CD3, especially in CD8 T cells.
About a quarter of circulating T cells lacked expression of CD3
above background, and in cells that had some expression, it was
significantly downmodulated. However, upregulation of CD3 expression
occurred over 6 to 16 hours in culture and coincided with restoration
of viral-specific cytotoxicity.
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MATERIALS AND METHODS |
Subjects.
Subjects were healthy volunteers or HIV-1 seropositive patients of
varied disease stages (Table 1). Nineteen
subjects had had no clinical symptoms of HIV infection, and 6 subjects
(601, 602, 604, 605, 6155, and 6159) had CD4 counts above
600/mm3. Six patients (216, 221, 228, 235, 354, and 355)
met the Centers for Disease Control (CDC) criteria for
AIDS.20 Subjects no. 601 and 6225 were recent
seroconverters (3 and 8 months earlier, respectively) and subjects no.
602, 6155, and 6159 could be considered slow progressors. Informed
consent was obtained from each subject. This study was approved by the
Center for Blood Research Institutional Review Board. Samples were
either freshly obtained or cryopreserved using a programmed cell
freezer (Gordinier Model 9000; Gordinier, Roseville, MI). Flow
cytometry results obtained from thawed cells were comparable with those
from freshly isolated cells in two samples studied.
Flow cytometry.
For CD3 staining, PBMCs (2 to 10 × 105/tube),
isolated by Ficoll-Hypaque density centrifugation from heparinized
blood, were suspended in 50 µL fluorescence-activated cell sorting
(FACS) buffer (2% fetal calf serum [FCS], 0.2 mg/mL NaN3
in phosphate-buffered saline [PBS]) to which 4 µL phycoerythrin
(PE)-conjugated CD3 SK7 monoclonal antibodies (MoAbs; Becton
Dickinson, Mountain View, CA) or isotype-matched control was added.
After incubation for 20 minutes at 4°C, cells were washed with 1 mL
FACS buffer and resuspended in FACS buffer with 1% formaldehyde before
analysis. For CD3 and grnA staining, cells were resuspended in 50 µL Hanks' balanced salt solution (HBSS) and permeabilized using the
Caltag Laboratories (Burlingame, CA) Fix and Perm Kit according to the manufacturer's protocol. Fixed cells were incubated for 15 minutes at
room temperature with either 2 µL CD3 MoAb 6B10.2 (Santa Cruz, Santa Cruz, CA), a 1:5 dilution of grnA CB9 MoAb culture
supernatant,21 or 2.5 µL MsIgG1 isotype-matched control
antibody (Coulter, Hialeah, FL). After washing with 5 mL HBSS, cells
were stained with 2 µL PE-conjugated F(ab )2 goat
antimouse Ig (DAKO, Carpenteria, CA). For some samples, direct CD3
staining was performed with fluorescein isothiocyanate
(FITC)-conjugated 6B10.2 (Santa Cruz) and elimination of the second
step. After two further washes, cells were resuspended in PBS with 1%
formaldehyde for analysis. Flow cytometry analysis was performed on a
tightly gated lymphocyte population using FACScalibur (Becton
Dickinson). Cellquest (Becton Dickinson) software was used to overlay
and subtract the histograms of the control antibody-stained cells from
the CD3-stained cells. For each sample the ratio of the number of cells
staining for CD3 to those staining for CD3 was calculated. CD3
three-color staining was done as previously described for CD3 single
staining before the addition of 2 µL CD4-Cy5 (Pharmingen, San Diego,
CA) and 2 µL CD8-FITC (Immunotech, Westbrook, ME), 4 µL CD20-FITC
(Becton Dickinson), and 2 µL CD3-Cy5 (Immunotech), or IgG-FITC and
-Cy5 conjugated controls. The samples were incubated for 15 minutes at
4°C, washed with 5 mL HBSS, and resuspended in PBS with 2% FCS and
1% formaldehyde for analysis.
Cell lines.
T-cell lines were generated by culture of PBMCs at 1 × 106/mL in T-cell medium (RPMI 1640 supplemented with 2 mmol/L glutamine, 2 mmol/L HEPES, 100 U/mL penicillin, 100 µg/mL
streptomycin, and 50 µmol/L  -mercaptoethanol) to which was added
10% FCS. In some cases, varying concentrations of recombinant human
IL-2 (Cetus, Emeryville, CA) or antihuman IL-2-neutralizing antibody
5334.21 (R&D Systems, Minneapolis, MN) was added at the initiation of culture. Autologous B lymphoblastoid cell lines (B-LCLs) were generated
for each subject using standard methods.
Cytotoxicity assay.
HIV-specific cytotoxicity of PBMCs, freshly isolated or after overnight
culture, was analyzed by 4-hour 51Cr release assay against
autologous B-LCL targets infected with vaccinia recombinant vectors
encoding HIV genes as previously described.9 Target cells
were infected with vaccinia vectors encoding lacZ (vSC8),
env of the BH8 isolate of HIV-1IIIB (vPE16), gag of the HXB.2 subclone (vDK1), and all but the last 22 residues of HXB.2 RT (vCF21).6,9,22
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RESULTS |
HIV-specific cytotoxicity is greatly enhanced by overnight in vitro
culture and the increase is IL-2 dependent.
Although antiviral HIV-specific cytotoxicity is detectable in freshly
isolated PBMCs from some HIV-infected donors, more commonly, antiviral
cytotoxicity only reaches significant levels after in vitro culture. In
previous studies we measured large increases in viral-specific
cytotoxicity after phytohemagglutinin stimulation and in vitro culture
for 2 to 3 weeks in the presence of IL-2. To study the kinetics and
IL-2 dependence of the emergence of viral-specific cytotoxic activity
in vitro, we measured cytotoxicity against HIV-expressing autologous
targets after overnight and 3-day culture in IL-2-containing media by
PBMCs from five subjects whose freshly isolated PBMCs lacked
significant activity. Representative data from four HIV-infected
subjects and a representative healthy donor are shown in
Figs 1 and 2.
Antiviral cytotoxic activity emerged in the cultures from HIV-infected
donors in an IL-2-dependent manner within 16 hours to levels
comparable with those detected after 2 to 3 weeks of culture. At
intermediate concentrations of IL-2 (30 and 150 IU/mL), HIV-specific
cytotoxicity was somewhat increased after 3 days compared with
overnight, but at that time nonspecific
lymphokine-activated killer (LAK)-like activity also began
to be detected as lysis of control vaccinia-infected B-LCLs. Because
one could expect, at most, one cell division in overnight cultures, the
development of antiviral cytotoxicity could not depend on the selective
proliferation of HIV-specific precursor CTLs.
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| Fig 1.
HIV-specific cytotoxicity by PBMCs from a representative
HIV-infected donor (no. 234; A) is below background (10%) for freshly isolated samples but rapidly develops after culture overnight or for 3 days in IL-2. Healthy donor PBMCs (B) have no HIV-specific cytotoxicity
before or after culture but develop LAK-like activity in an
IL-2-dependent manner (as evidenced by the lysis of control vaccinia
infected autologous B-LCLs). Cytotoxicity is measured by 4-hour
51Cr release assay at an effector:target ratio of 50:1
against autologous targets infected with vaccinia recombinant virus
expressing HIV gp160 (vPE16), RT (vCF21), and gag (vDK1). The control
vaccinia (vSC8) expresses the lacZ gene.
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| Fig 2.
HIV-specific cytotoxicity increases after overnight
culture in an IL-2-dependent manner from PBMCs of HIV-infected donors 228 (A), 237 (B), and 307 (C). Cytotoxicity is measured as in Fig 1
against targets expressing lacZ control (vSC8), gp160 (vPE16), RT
(vCF21), and gag (vDK1). The percent of CD8 T cells that express CD3
increases concomitantly.
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Freshly isolated CD8 T lymphocytes from HIV-infected donors have a
high frequency of expression of the CTL granule protein, grnA.
One possible reason for the lack of specific cytotoxicity of
circulating peripheral blood lymphocytes (PBLs) could have been lack of
the cytolytic machinery, which consists of a pore-forming protein,
perforin, and several CTL-specific serine proteases, termed granzymes,
which are released when a CTL encounters a target cell.23-25 Precursor CTLs, which have not encountered
specific antigens, lack cytotoxic proteins, which are expressed within 1 day of antigenic stimulus. We used three-color flow cytometry analysis of permeabilized PBMCs indirectly stained, with a mouse MoAb
CB921 for the most abundant human CTL granzyme
grnA26 and directly stained for CD3 and CD16 or CD4 and CD8
expression (Fig 3). In healthy donors, less
than 10% of circulating CD4 cells, up to 50% of CD8 cells, and
greater than 95% of CD16+ cells (mostly NK cells) stained
for grnA. In 17 HIV-infected donors covering a range of disease states,
the mean percent of CD4 and CD8 cells that expressed grnA was
significantly higher, although the increases in this small sample did
not correlate with clinical status. The percent of grnA-staining CD4
cells was 22% ± 13% in HIV-infected subjects versus 7% ± 3%
in healthy controls (P = .003, 2-sided
t-test). The difference was even greater for CD8 T cells: 71% ± 12% in HIV-infected subjects versus 41% ± 10% in
healthy subjects (P = .000001). This is consistent with the known high frequency of activated circulating CD8 CTLs, expressing human leukocyte antigen (HLA)-DR and CD38 in HIV-infected
subjects.11 Virtually all NK cells in both groups stained
for grnA. Therefore, lack of antiviral cytotoxicity by freshly isolated
PBMCs was not because of lack of cytolytic protein expression.
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| Fig 3.
HIV-infected subjects have an increased frequency of T
cells that stain for the cytolytic granule protease grnA. (A) CB9 MoAb stains about 25% of the circulating lymphocytes of a healthy donor but
stains the majority of circulating lymphocytes in HIV-infected subjects. (B) An increased number of circulating CD4 ( ), CD3 ( ),
and CD8 ( ) T cells in HIV-infected subjects (graphed for representative subjects in order of increasing immunodeficiency) contain the cytolytic effector molecule, grnA. CD16+
( ) NK cells from healthy and HIV-infected donors uniformly contain grnA.
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Circulating T cells from HIV-infected donors downmodulate CD3
expression.
Lymphocytes isolated from tumor-bearing mice and from patients with a
variety of tumors have defective T-cell function because of
downregulation of CD3, the signaling component of the TcR. We tested
whether or not a similar defect might occur in HIV-infected donors.
Because CD3 is mostly intracytoplasmic and antibodies to CD3
recognize determinants not accessible to the cell surface, cells were
permeabilized before immunofluorescent staining. PBMCs were directly
stained with immunofluorescent antibody to cell surface CD3 or were
permeabilized and stained with antibody to CD3 or control. The
histograms of gated lymphocytes stained for and control antibody
were subtracted to obtain the number of cells expressing (Fig 4A). In PBMCs from healthy donors, the number of cells expressing CD3 corresponded to the number of CD3-expressing cells (Fig 4C). The ratio of CD3-expressing cells to CD3-expressing cells in 14 healthy donor samples was 1.01 ± 0.07, not significantly different from the expected value of 1, if the
number of NK cells can be ignored.
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| Fig 4.
CD3 is downmodulated in circulating lymphocytes from
most HIV-infected donors. (A) The isotype-matched control antibody
histogram is subtracted from the CD3 histogram (shaded) to obtain
the number of + cells. In normal donor P14 and
asymptomatic healthy HIV-infected subject 6159, the number of
-staining cells is comparable with the number of cells staining for
CD3 . However, in donor no. 214, who has oral hairy leukoplakia and
thrush, CD3 expression is downmodulated. (B) CD3 staining for
PBLs from 28 HIV-seropositive donors, graphed in order of declining CD4
counts. The dashed lines represent the normal range (C). (D) The
percent of T cells that do not stain for increases as the CD4 count
falls. (E) CD3 downmodulation correlates with CDC disease stage. The
ratio for stage A donors, 0.80 ± 0.14, is significantly lower than
that of HIV-seronegative healthy donors (*P < .00001) but
significantly higher than that of symptomatic stage B donors 0.55 ± 0.09 (**P < .001).
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PBMCs from 28 HIV-infected donors of varying disease stages (Table 1)
were analyzed. All but 8 of these subjects had evidence of
immunodeficiency by a CD4 count <500 cells/mm3 or
clinical symptoms. The ratio of CD3-expressing cells to
CD3-expressing cells was significantly reduced to 0.74 ± 0.16 (Fig 4B). This was highly significant compared with healthy donors by
2-sided t-test (P < .0000005). CD3 expression also
correlated with CD4 count, with a higher fraction of cells lacking as the CD4 count dropped (r = 0.55, P < .005, Fig 4D), but
did not correlate with plasma viremia in this sample.
The ratio of CD3-expressing cells/CD3-expressing cells also
correlated with the HIV disease stage as defined by the
CDC20 (Fig 4E). The ratio for 19 asymptomatic HIV-infected
donors (stage A) was 0.80 ± 0.14, which was significantly different
from healthy donors (P = .00001). Only 2 subjects (subjects no.
6159 and 6181) had values in the normal range, and they had CD4 counts
above 500/mm3. The ratio greater than 1 for subject 6159 could be attributed to a high percent of circulating NK cells (25% of
PBL CD16+), which expressed but not CD3. Six donors
with minor symptoms of HIV infection (stage B) had significantly lower
ratios (0.55 ± 0.09, P < .001 compared with stage A). The
three donors with a history of major opportunistic infections, had a
somewhat restored ratio (0.74 ± 0.02), but the number of subjects
was too few to draw any conclusions.
CD8 T cells preferentially downmodulate CD3.
To determine whether all T cells, or a particular subset, had
downregulated CD3, we analyzed PBMCs from 20 HIV-infected and 7 healthy donors by three-color staining for CD4 and CD8 or CD20 and
CD3 together with CD3. Each subject was analyzed using CD20 B
cells as an internal negative control to set quadrant parameters (Fig 5A). Simultaneous staining with CD3
and CD3 gave comparable results with the method described
previously. In most HIV-infected subjects, CD8, but not CD4 T cells had
downregulated to the extent that a sizable fraction of CD8 T cells
did not stain for above background. Three AIDS patients also showed
a slight decrease in the CD4 T-cell subset (Fig 5B). The percentage of
CD8 T cells staining for in 20 HIV-infected donor PBMCs was 63% ± 22% compared with 91% ± 4% in healthy donors (P = .004), whereas the percentage of CD4 cells expressing was only
slightly reduced: 91% ± 6% for HIV-infected versus 96% ± 2%
for controls (P = .05; Table 2).
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| Fig 5.
CD3 is downmodulated to a greater extent in CD8 T
cells than CD4 T cells. Gated lymphocytes were analyzed for triple
staining with antibodies to CD3 with CD3 and CD20 or CD4 and CD8.
(A) Profile of a healthy donor (I), asymptomatic, slow-progressor subject no. 6156 (II), and AIDS patient no. 355 (III). (B)
Representative results from healthy donors, asymptomatic HIV-infected
donors and AIDS patients show progressive downmodulation of in CD8 more than CD4 T cells. The percent of CD20 B cells (), CD3 T cells (), CD4 T cells () and CD8 T cells () that costain with is shown.
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CD4 and CD8 T cells have reduced levels of CD3.
Although most CD8+ and CD4+ T cells stained
above background for CD3, the levels of expression for both subsets
were reduced (Table 2). The mean fluorescence intensity for CD8 T
cells was reduced to 39% of normal (24 ± 11 v 61 ± 19;
P < .002) and for CD4 cells to 58% of normal (53 ± 25 v 92 ± 33; P = .06). The CD3 mean
fluorescence of CD8 and CD4 subsets also correlated significantly with
CD4 counts with correlation coefficients of 0.70 (P = .01) and
0.64 (P < .05), respectively. Interestingly, CD4 T cells from
healthy donors have higher CD3 and mean fluorescence intensity
than CD8 T cells. This may partly explain why the number of CD4 T cells
in HIV infection that did not stain above background was low. CD3 expression must be reduced more in CD4 than in CD8 T cells to measure
below the detection threshold.
CD3 expression increases after overnight culture in an
IL-2-dependent manner.
Because development of antiviral cytotoxicity during overnight culture
required the addition of exogenous IL-2, we measured CD3 expression
after overnight culture in the presence of increasing concentrations of
IL-2. We found that CD3 expression in PBLs from three donors (no.
228, 237, and 307) also increased when calculated as a percent of T
cells staining for above threshold or as mean fluorescence
intensity of T cells (data not shown) in an IL-2-dependent manner (Fig
2). The change in expression parallels the in vitro increase in
cytotoxicity. The increase in CD3 expression was detectable
beginning at 6 to 10 hours after in vitro culture in three HIV-infected
subjects (data not shown).
In some less advanced subjects, CD3 expression increased partially
in vitro even in the absence of adding exogenous IL-2. Data from four
asymptomatic subjects (CD4 counts 493 to 840 cells/mm3) are
shown in Fig 6. The percent of CD8 T cells
that stained above threshold for CD3 increased in culture for the
two patients with higher CD4 counts (604 and 605) but decreased in the
two subjects with CD4 counts below 500/mm3 (502 and 503).
The mean percent of -staining CD8 T cells was not changed after
overnight culture (67% ± 5% v 69% ± 10%; P = .76). Because the subjects whose percentage increased in vitro had
higher numbers of CD4 T cells capable of producing endogenous IL-2, we
determined whether reexpression could be blocked in the presence of
an IL-2 blocking antibody. The blocking antibody reduced CD3
expression after culture in all four subjects to 59% ± 9%, a
significant change compared with the cultures without antibody
(P = .01). Similarly, when we added exogenous IL-2 (300 IU/mL),
the percent of CD8 T cells staining for CD3 increased significantly
to 81% ± 3% (P = .02 compared with fresh T cells). This
increase was blocked when the IL-2 blocking antibody was added at the
beginning of culture; the percent of staining CD8 T cells decreased to
65% ± 6% (P = .04 compared with cultures without
antibody), a level comparable with that of fresh cells. These results
confirmed a role for IL-2 in the parallel defects of expression and
antiviral cytotoxic function.
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| Fig 6.
CD3 reexpression in vitro is inhibited by an
IL-2-blocking antibody. T cells from four asymptomatic HIV-infected
donors (502,  ; 503, X; 604,  ; 605, ) cultured overnight with
or without exogenous IL-2 (300 IU/mL) and/or anti-IL-2
blocking antibody 5334.21 (30 µg/mL). The percent of CD8 T cells
staining above background for CD3 is shown. Statistically
significant changes are indicated.
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DISCUSSION |
We have found that expression is downregulated in CD8, and to a
lesser extent in CD4 T cells from most HIV-infected subjects and that
it upregulates after overnight culture in serum-containing media in an
IL-2-dependent manner. This appears to occur simultaneously with
detection of HIV-specific cytotoxicity, which is also IL-2 dependent.
The kinetics of reappearance in vitro beginning at about 6 hours
explains why laboratories that assayed PBMCs for antiviral cytotoxicity
in 6- to 16-hour assays detected a much greater frequency of responders
than laboratories that used 4-hour assays. Impaired HIV-specific
cytotoxicity in vivo is likely due at least in part to a defect in T
helper IL-2 secretion.
Our results are consistent with a recent study that found a signaling
defect in the circulating T cells of HIV-infected
subjects.27 Using immunoprecipitation and Western blotting,
kinase activities of lck, fyn, and ZAP70 were found to be decreased in
HIV-infected patients at varying disease stages but not in a group of
five long-term nonprogressors. This decrease in kinase activity was related to a conformational change because some but not all antibodies showed decreased reactivity to these proteins from PBLs from
HIV-infected donors, and antibody reactivity was restored after protein
treatment with dithiothreitol. These abnormalities were found in both
CD4 and CD8 cells from two AIDS patients with less than 100 CD4
cells/mm3. chain downmodulation was also found by
Western blotting in T cells from several acutely infected patients,
recently infected patients, and AIDS patients, although CD4 and CD8
subsets were not separately examined. Downmodulation of presumably
increased the threshold for T-cell activation.
Although high concentrations of exogenous IL-2 can overcome CD3
downmodulation in vitro, the causes of its downregulation in vivo may
be multifactorial. The defect in T-helper cell function that is the
hallmark of HIV infection is likely to play a significant role.
Functional defects in the proliferative response to recall antigens and
to HIV occur early in the disease before the onset of symptoms at the
time when we have found defects in CD3 expression.28
T-cell dysfunction in HIV infection has been extensively studied with
most studies focused on the effects of HIV infection or of HIV gene
products on CD4 T cells. Cell surface CD4 is a key regulator of CD4
T-cell activation. When CD4 is ligated together with the TcR, it
enhances T-cell activation; however, when it is ligated independently
it inhibits subsequent TcR activation or can initiate CD4 T-cell death.
Cross-linking of cell surface CD4 with HIV gp120 and antibody to gp120
has been shown to inhibit TcR activation events including
phosphorylation of CD3, lck and fyn, and Ca++
influx.29-33 Expression of HIV nef within CD4 T cells has
also been shown to inhibit T-cell activation, probably by several
mechanisms including downmodulation of cell surface CD4 and by
interaction of a nef central SH3 binding surface to lck and possibly
other TcR-signaling molecules.34-38 These HIV gene products
have been implicated in T-cell dysfunction of CD4 T cells but are
unlikely to be directly related to the phenomenon we are studying,
which disproportionally affects CD8 T cells. However, coculture of CD4 T cells with HIV-infected T-cell hybridomas and monocytes has been
shown to reduce IL-2 production.39 This direct effect on IL-2 secretion, together with the reduced CD4 T-cell number and selective deficit in antigen-specific CD4 T cells characteristic of HIV
infection, may be important contributing factors to the downmodulation
of CD3. Another HIV gene product, tat, has been shown to bind to the
cell surface ectoenzyme dipeptidyl aminopeptidase type IV (DP IV or
CD26) and to inhibit antigen-specific and anti-CD3 T-cell
proliferation. Interestingly the antigen-specific inhibition could be
overcome by exogenous IL-2.40,41 Because tat protein has
been shown to be secreted from HIV-infected cells, a possible role for
tat in CD3 downmodulation of CD4 and CD8 T cells is worth exploring.
Other T-cell defects during HIV infection may be related to CD3
downmodulation. These include the increased apoptosis of CD4 and CD8 T
cells in the blood of HIV-infected donors (with rescue with exogenous
IL-2)42 and the increased number of memory CD4 and CD8 T
cells and activated CD28 HLA-DR+CD8 T
cells.10-12 CD8 T cells from healthy and HIV-infected
donors that are CD28 have reduced proliferation to
anti-CD3, which increases in the presence of IL-2.43,44
The reasons for CD3 downregulation in TILs and PBLs from some cancer
patients have not been elucidated, although several reports may provide
clues for fruitful avenues of research. In one report, coculture of
PBMCs from healthy donors with a human lung cancer cell line induced
downmodulation of chain expression, as well as the p56lck and ZAP70
tyrosine kinases. This effect required direct cell-to-cell contact, so
it is probably not mediated solely by cytokines. However, coculture
with the same tumor cells transfected with IL-2, but not IL-7,
granulocyte-macrophage colony-stimulating factor, or tumor necrosis
factor- , was able to reverse the downregulation.45
In another report, macrophages that accumulated in the spleens of
tumor-bearing mice were able to induce downregulation, also in a
contact-dependent manner, in T cells from healthy mice. Moreover,
normal macrophages activated by zymosan A and lipopolysaccharide were
also able to induce downregulation from healthy T
cells.46 Further work by this group showed that treatment
of macrophages from tumor-bearing mice with the antioxidant N-acetyl
cysteine blocked their ability to induce downregulation, and
treatment with oxidants such as H2O2 induced
downmodulation.47 Because chronic macrophage activation
and oxidant stress are characteristic features of HIV
infection,48 a possible role for either of these in the
phenomenon we have described in HIV infection merits further inquiry.
In another report, costimulation with cross-linked CD3 and CD28 of
-downmodulated T cells from Hodgkin's disease patients in vitro induced the reexpression of chain.16 Because a
high fraction of circulating CD8, but not CD4, T cells in HIV infection lacked expression of CD28,12 it is possible that this
result might also be relevant to the CD3 downmodulation that we have found predominantly in CD8 T cells in HIV-infected donors.
Downregulation of CD3 in CD8 T cells and consequent loss of their
normal functional activity is likely to have significant adverse
consequences on control of viral replication in HIV-infected individuals. This result may help explain why the high frequency of
HIV-specific precursor CTLs fails to control HIV replication. We have
presented preliminary evidence that suggests that downregulation is
an early manifestation of HIV disease. It remains to be determined when
CD3 downregulation occurs in the course of the infection, whether it
occurs in long-term nonprogressors and whether it is reversible by
treatment with highly effective combination antiretroviral drugs.
CD3 expression was normal in two subjects we tested with no clinical
signs of immunodeficiency. Preliminary study of two patient cohorts
treated early with intensive, effective antiretroviral therapy that
reduced plasma viremia to undetectable levels for sustained periods,
suggested that the defect in expression can be reversed. If so, the
prospects for immune control of residual viral reservoirs and their
possible eventual elimination will be significantly improved. A flow
cytometry-based assay of relative expression of CD3 and CD3 might
be a useful tool to monitor immune recovery during drug therapy.
These findings have implications for the design of effective
immune-based therapies, especially cellular infusion therapy with CD8 T
cells.49-51 For one, it provides a rationale for removing T
cells and culturing them in IL-2 briefly to upregulate expression and antiviral function. However, it is unlikely that the infused cells
will have a sustained effect if they subsequently downregulate expression and do not continue to function in vivo. Our results also
provide a possible additional rationale for IL-2
therapy52,53; an added benefit to IL-2 infusion, in
addition to increasing CD4 counts, may be improved CD8 T-cell function.
Whether this occurs in vivo, as we observed in our short-term in vitro
assays, needs to be explored. The possible salutary effects of related cytokines, such as IL-12 or IL-15, to in vitro reexpression also
remains to be studied.
CD3 downmodulation in HIV infection and cancer may be examples of a
more common mechanism for controlling an exuberant immune response in
the setting of chronic inflammation or antigen excess. Although
mechanisms for regulation of the CD4 T-cell response in the setting of
antigenic excess have been well studied, little is known about how the
CD8 T-cell response might be modulated. It is possible that induction
of CD4 T-cell anergy induces CD8 T-cell downmodulation. The
consequent inhibition of TcR signaling may be an important mechanism
for controlling CD8 T-cell cytolysis.
| |
FOOTNOTES |
Submitted April 24, 1997;
accepted September 17, 1997.
Supported by a Pew Scholar Award in the Biomedical Sciences and
National Institutes of Health Grant No. U19-AI36611 (J.L.).
Address reprint requests to Judy Lieberman, MD, PhD, The Center for
Blood Research, 800 Huntington Avenue, Boston, MA 02115.
The publication costs of this article were defrayed in part by page
charge payment. This article must therefore be hereby marked
"advertisement" in accordance with 18 U.S.C. section 1734 solely
to indicate this fact.
| |
ACKNOWLEDGMENT |
We thank M. Perales, H. Jessen, F. Lori, and J. Lisziewicz for patient
samples; H. Sprang and F. Emspak for expert technical assistance; and
P. Shankar for helpful discussions.
| |
REFERENCES |
1.
Hoffenbach A,
Langlade-Demoyen P,
Dadaglio G,
Vilmer E,
Michel F,
Mayaud C,
Autran B,
Plata F:
Unusually high frequencies of HIV-specific cytotoxic T lymphocytes in humans.
J Immunol
142:452,
1989[Abstract]
2.
Moss PA,
Rowland-Jones SL,
Frodsham PM,
McAdam S,
Giangrande P,
McMichael AJ,
Bell JI:
Persistent high frequency of human immunodeficiency virus-specific cytotoxic T cells in peripheral blood of infected donors.
Proc Natl Acad Sci USA
92:5773,
1995[Abstract/Free Full Text]
3.
Altman JD,
Moss PAH,
Goulder PJR,
Barouch DH,
McHeyzer-Williams MG,
Bell JI,
McMichael AJ,
Davis MM:
Phenotypic analysis of antigen-specific T lymphocytes.
Science
274:94,
1996[Abstract/Free Full Text]
4.
Ho DD,
Neumann AU,
Perelson AS,
Chen W,
Leonard JM,
Markowitz M:
Rapid turnover of plasma virions and CD4 lymphocytes in HIV-1 infection.
Nature
373:123,
1995[Medline]
[Order article via Infotrieve]
5.
Wei X,
Ghosh SK,
Taylor ME,
Johnson VA,
Emini EA,
Deutsch P,
Lifson JD,
Bonhoeffer S,
Nowak MA,
Hahn BH,
Saag MS,
Shaw GM:
Viral dynamics in human immunodeficiency type 1 infection.
Nature
373:117,
1995[Medline]
[Order article via Infotrieve]
6.
Walker BD,
Chakrabarti S,
Moss B,
Paradis TJ,
Flynn T,
Durno AG,
Blumberg RS,
Kaplan JC,
Hirsch MS,
Schooley RT:
HIV-specific cytotoxic T lymphocytes in seropositive individuals.
Nature
328:345,
1987[Medline]
[Order article via Infotrieve]
7.
Koup RA,
Sullivan JL,
Levine PH,
Brettler D,
Mahr A,
Mazzara G,
McKenzie S,
Panicali D:
Detection of major histocompatibility complex class I-restricted, HIV-specific cytotoxic T lymphocytes in the blood of infected hemophiliacs.
Blood
73:1909,
1989[Abstract/Free Full Text]
8.
Riviere Y,
Tanneau-Salvadori F,
Regnault A,
Lopez O,
Sansonetti P,
Guy B,
Kieny MP,
Fournel JJ,
Montagnier L:
Human immunodeficiency virus-specific cytotoxic responses of seropositive individuals: Distinct types of effector cells mediate killing of targets expressing gag and env proteins.
J Virol
63:2270,
1989[Abstract/Free Full Text]
9.
Lieberman J,
Fabry JA,
Kuo MC,
Earl P,
Moss B,
Skolnik PR:
Cytotoxic T lymphocytes from HIV-1 seropositive individuals recognize immunodominant epitopes in Gp160 and reverse transcriptase.
J Immunol
148:2738,
1992[Abstract]
10.
Vanham G,
Kestens L,
Gigase P,
Colebunders R,
Vandenbruaene M,
Brijs L,
Ceuppens JL:
Evidence for circulating activated cytotoxic T cells in HIV-infected subjects before the onset of opportunistic infections.
Clin Exp Immunol
82:3,
1990[Medline]
[Order article via Infotrieve]
11.
Ho HN,
Hultin LE,
Mitsuyasu RT,
Matud JL,
Hausner MA,
Bockstoce D,
Chou CC,
O'Rourk S,
Taylor JM,
Giorgi JV:
Circulating HIV-specific CD8+ cytotoxic T cells express CD38 and HLA-DR antigens.
J Immunol
150:3070,
1993[Abstract]
12.
Saukkonen JJ,
Kornfeld H,
Berman JS:
Expansion of a CD8+CD28 cell population in the blood and lung of HIV-positive patients.
J Acquir Immune Defic Syndr
6:1194,
1993
13.
Mizoguchi HO,
Shea JJ,
Longo DL,
Loeffler CM,
McVicar DW,
Ochoa AC:
Alterations in signal transduction molecules in T lymphocytes from tumor-bearing mice.
Science
258:1795,
1992[Abstract/Free Full Text]
14.
Finke JH,
Zea AH,
Stanley J,
Longo DL,
Mizoguchi H,
Tubbs RR,
Wiltrout RH,
O'Shea JJ,
Kudoh S,
Klein E,
Bukowski RM,
Ochea AC:
Loss of T-cell receptor zeta chain and p56lck in T-cells infiltrating human renal cell carcinoma.
Cancer Res
53:5613,
1993[Abstract/Free Full Text]
15.
Massaia M,
Attisano C,
Beggiato E,
Bianchi A,
Pileri A:
Correlation between disease activity and T-cell CD3 zeta chain expression in a B-cell lymphoma.
Br J Haematol
88:886,
1994[Medline]
[Order article via Infotrieve]
16.
Renner C,
Ohnesorge S,
Held G,
Bauer S,
Jung W,
Pfitzenmeier JP,
Pfreundschuh M:
T cells from patients with Hodgkin's disease have a defective T-cell receptor zeta chain expression that is reversible by T-cell stimulation with CD3 and CD28.
Blood
88:236,
1996[Abstract/Free Full Text]
17.
Weiss A,
Littman DR:
Signal transduction by lymphocyte antigen receptors.
Cell
76:263,
1994[Medline]
[Order article via Infotrieve]
18.
Exley M,
Terhorst C,
Wileman T:
Structure, assembly and intracellular transport of the T cell receptor for antigen.
Sem Immunol
3:283,
1991[Medline]
[Order article via Infotrieve]
19.
Ono S,
Ohno H,
Saito T:
Rapid turnover of the CD3 zeta chain independent of the TCR-CD3 complex normal T cells.
Immunity
2:639,
1995[Medline]
[Order article via Infotrieve]
20. Centers for Disease Control: 1993 revised classification system
for HIV infection and expanded surveillance case definition for AIDS
among adolescents and adults. MMWR Morb Mortal Wkly Rep 41:1, 1993
21.
Beresford PJ,
Kam C-M,
Powers JC,
Lieberman J:
Recombinant human granzyme A binds to two putative HLA-associated proteins and cleaves one of them.
Proc Natl Acad Sci USA
94:9285,
1997[Abstract/Free Full Text]
22.
Walker BD,
Flexner C,
Paradis TJ,
Fuller TC,
Hirsch MS,
Schooley RT,
Moss B:
HIV-1 reverse transcriptase is a target for cytotoxic T lymphocytes in infected individuals.
Science
240:64,
1988[Abstract/Free Full Text]
23.
Pasternack MS,
Eisen HN:
A novel serine protease expressed by cytotoxic T lymphocytes.
Nature
314:743,
1985[Medline]
[Order article via Infotrieve]
24.
Podack ER,
Young JD-E,
Cohn ZA:
Isolation and biochemical and functional characterization of perforin 1 from cytolytic T cell granules.
Proc Natl Acad Sci USA
82:8629,
1985[Abstract/Free Full Text]
25.
Jenne DE,
Tschopp J:
Granzymes, a family of serine proteases released from granules of cytolytic T lymphocytes upon T cell receptor stimulation.
Immunol Rev
103:53,
1988[Medline]
[Order article via Infotrieve]
26.
Gershenfeld HK,
Weissman IL:
Cloning of a cDNA for a T cell-specific serine protease from a cytotoxic T lymphocyte.
Science
232:854,
1986[Abstract/Free Full Text]
27.
Stefanova I,
Saville MW,
Peters C,
Cleghorn FR,
Schwartz D,
Venzon DJ,
Weinhold KJ,
Jack N,
Bartolomew C,
Blattner WA,
Yarchoan R,
Bolen JB,
Horak ID:
HIV infection Induced posttranslational modification of T cell signaling molecules associated with disease progression.
J Clin Invest
98:1290,
1996[Medline]
[Order article via Infotrieve]
28.
Shearer GM,
Bernstein DC,
Tung KS,
Via CS,
Redfield R,
Salahuddin SZ,
Gallo RC:
A model for the selective loss of major histocompatibility complex self-restricted T cell immune responses during the development of acquired immune deficiency syndrome (AIDS).
J Immunol
137:2514,
1986[Abstract]
29.
Baier-Bitterlich G,
Baier G,
Gulbins E,
Coggeshall KM,
Altman A:
The role of p56lck in CD4-mediated suppression of CD3-induced early signaling events in T lymphocytes.
Life Sci
56:1287,
1995[Medline]
[Order article via Infotrieve]
30.
Jabado N,
Pallier A,
Le Deist F,
Bernard F,
Fischer A,
Hivroz C:
CD4 ligands inhibit the formation of multifunctional transduction complexes involved in T cell activation.
J Immunol
158:94,
1997[Abstract]
31.
Goldman F,
Crabtree J,
Hollenback C,
Koretzky G:
Sequestration of p56(lck) by gp120, a model for TCR desensitization.
J Immunol
158:2017,
1997[Abstract]
32.
Briand G,
Barbeau B,
Tremblay M:
Binding of HIV-1 to its receptor induces tyrosine phosphorylation of several CD4-associated proteins, including the phosphatidylinositol 3-kinase.
Virology
228:171,
1997[Medline]
[Order article via Infotrieve]
33.
Morio T,
Chatila T,
Geha RS:
HIV glycoprotein gp120 inhibits TCR-CD3-mediated activation of fyn and lck.
Int Immunol
9:53,
1997[Abstract/Free Full Text]
34.
Aiken C,
Konner J,
Landau NR,
Lenburg ME,
Trono D:
Nef induces CD4 endocytosis: Requirement for a critical dileucine motif in the membrane-proximal CD4 cytoplasmic domain.
Cell
76:853,
1994[Medline]
[Order article via Infotrieve]
35.
Baur AS,
Sawai ET,
Dazin P,
Fantl WJ,
Cheng-Mayer C,
Peterlin BM:
HIV-1 Nef leads to inhibition or activation of T cells depending on its intracellular localization.
Immunity
1:373,
1994[Medline]
[Order article via Infotrieve]
36.
Jabado N,
Le Deist F,
Fisher A,
Hivroz C:
Interaction of HIV gp120 and anti-CD4 antibodies with the CD4 molecule on human CD4+ T cells inhibits the binding activity of NF-AT, NF-kappa B and AP-1, three nuclear factors regulating interleukin-2 gene enhancer activity.
Eur J Immunol
24:2646,
1994[Medline]
[Order article via Infotrieve]
37.
Collette Y,
Dutartre H,
Benziane A,
Romas-Morales Benarous R,
Harris M,
Olive D:
Physical and functional interaction of Nef with Lck. HIV-1 Nef-induced T-cell signaling defects.
J Biol Chem
271:6333,
1996[Abstract/Free Full Text]
38.
Iafrate AJ,
Bronson S,
Skowronski J:
Separable functions of Nef disrupt two aspects of T cell receptor machinery: CD4 expression and CD3 signaling.
EMBO J
16:673,
1997[Medline]
[Order article via Infotrieve]
39.
Yoo J,
Chen H,
Kraus T,
Hirsch D,
Polyak S,
George I,
Sperber K:
Altered cytokine production and accessory cell function after HIV-1 infection.
J Immunol
157:1313,
1996[Abstract]
40.
Subramanyam M,
Gutheil WG,
Bachovchin WW,
Huber BT:
Mechanism of HIV-1 Tat induced inhibition of antigen-specific T cell responsiveness.
J Immunol
150:2544,
1993[Abstract]
41.
Chirmule N,
Than S,
Khan SA,
Pahwa S:
Human immunodeficiency virus Tat induces functional unresponsiveness in T cells.
J Virol
69:492,
1995[Abstract]
42.
Gougeon ML,
Laurent-Crawford AG,
Hovanessian AG,
Montagnier L:
Direct and indirect mechanisms mediating apoptosis during HIV infection: Contribution to in vivo CD4 T cell depletion.
Semin Immunol
5:187,
1993[Medline]
[Order article via Infotrieve]
43.
Lewis DE,
Tang DS,
Adu-Oppong A,
Schober W,
Rodgers JR:
Anergy and apoptosis in CD8+ T cells from HIV-infected persons.
J Immunol
153:412,
1994[Abstract]
44.
Lloyd TE,
Yang L,
Tang DN,
Bennett T,
Schober W,
Lewis DE:
Regulation of CD28 costimulation in human CD8+ T cells.
J Immunol
158:1551,
1997[Abstract]
45.
Guarini A,
Riera L,
Cignetti A,
Montacchini L,
Massaia M,
Foa R:
Transfer of the interleukin-2 gene into human cancer cells induces specific antitumor recognition and restores the expression of CD3/T-cell receptor associated signal transduction molecules.
Blood
89:212,
1997[Abstract/Free Full Text]
46.
Aoe T,
Okamoto Y,
Saito T:
Activated macrophages induce structural abnormalities of the T cell receptor-CD3 complex.
J Exp Med
181:1881,
1995[Abstract/Free Full Text]
47.
Otsuji M,
Kimura Y,
Aoe T,
Okamoto Y,
Saito T:
Oxidative stress by tumor-derived macrophages suppresses the expression of CD3 zeta chain of T-cell receptor complex and antigen-specific T-cell responses.
Proc Natl Acad Sci USA
93:13119,
1996[Abstract/Free Full Text]
48.
Staal FJT,
Ela SW,
Roederer M,
Anderson MA,
Herzenberg LA:
Glutathione deficiency and HIV infection.
Lancet
339:909,
1992[Medline]
[Order article via Infotrieve]
49.
Ho M,
Armstrong J,
McMahon D,
Pazin G,
Huang XL,
Rinaldo C,
Whiteside T,
Tripoli C,
Levine G,
Moody D,
Okarma T,
Elder E,
Gupta P,
Tauxe N,
Torpey D,
Herberman R:
A phase 1 study of adoptive transfer of autologous CD8+ T lymphocytes in patients with acquired immunodeficiency syndrome (AIDS)-related complex or AIDS.
Blood
81:2093,
1993[Abstract/Free Full Text]
50.
Riddell SR,
Greenberg PD:
Therapeutic reconstitution of human viral immunity by adoptive transfer of cytotoxic T lymphocyte clones.
Curr Top Microbiol Immunol
189:9,
1994[Medline]
[Order article via Infotrieve]
51. Lieberman J, Skolnik PR, Parkerson GR, Fabry JA, Landry B,
Bethel J, Kagan J, DATRI 006 Study Team: Safety of autologous, ex
vivo-expanded HIV-specific cytotoxic T lymphocyte infusion in
HIV-infected patients. Blood 90:2196,1997
52.
Kovacs JA,
Baseler M,
Dewar RJ,
Vogel S,
Davey RT Jr,
Falloon J,
Polis MA,
Walker RE,
Stevens R,
Salzman NP,
Metcalf JA,
Masur H,
Lane HC:
Increases in CD4 T lymphocytes with intermittent courses of interleukin-2 in patients with human immunodeficiency virus infection. A preliminary study.
N Engl J Med
332:567,
1995[Abstract/Free Full Text]
53.
Jacobson EL,
Pilaro F,
Smith KA:
Rational interleukin 2 therapy for HIV positive individuals: Daily low doses enhance immune function without toxicity.
Proc Natl Acad Sci USA
93:10405,
1996[Abstract/Free Full Text]
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V. Lazarevic, D. Nolt, and J. L. Flynn
Long-Term Control of Mycobacterium tuberculosis Infection Is Mediated by Dynamic Immune Responses
J. Immunol.,
July 15, 2005;
175(2):
1107 - 1117.
[Abstract]
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A. Takahashi, M. G. V. Hanson, H. R. Norell, A. M. Havelka, K. Kono, K.-J. Malmberg, and R. V. R. Kiessling
Preferential Cell Death of CD8+ Effector Memory (CCR7-CD45RA-) T Cells by Hydrogen Peroxide-Induced Oxidative Stress
J. Immunol.,
May 15, 2005;
174(10):
6080 - 6087.
[Abstract]
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B. M. Badran, K. Kunstman, J. Stanton, M. Moschitta, A. Zerghe, H. Akl, A. Burny, S. M. Wolinsky, and K. E. Willard-Gallo
Transcriptional Regulation of the Human CD3{gamma} Gene: The TATA-Less CD3{gamma} Promoter Functions via an Initiator and Contiguous Sp-Binding Elements
J. Immunol.,
May 15, 2005;
174(10):
6238 - 6249.
[Abstract]
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L. Krymskaya, W.-H. Lee, L. Zhong, and C.-P. Liu
Polarized Development of Memory Cell-Like IFN-{gamma}-Producing Cells in the Absence of TCR {zeta}-Chain
J. Immunol.,
February 1, 2005;
174(3):
1188 - 1195.
[Abstract]
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A. F. Ochsenbein, S. R. Riddell, M. Brown, L. Corey, G. M. Baerlocher, P. M. Lansdorp, and P. D. Greenberg
CD27 Expression Promotes Long-Term Survival of Functional Effector-Memory CD8+ Cytotoxic T Lymphocytes in HIV-infected Patients
J. Exp. Med.,
December 6, 2004;
200(11):
1407 - 1417.
[Abstract]
[Full Text]
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W. J. Grossman, J. W. Verbsky, B. L. Tollefsen, C. Kemper, J. P. Atkinson, and T. J. Ley
Differential expression of granzymes A and B in human cytotoxic lymphocyte subsets and T regulatory cells
Blood,
November 1, 2004;
104(9):
2840 - 2848.
[Abstract]
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Y. Nishimura, M. Shimojima, E. Sato, Y. Izumiya, Y. Tohya, T. Mikami, and T. Miyazawa
Downmodulation of CD3{varepsilon} expression in CD8{alpha}+{beta}- T cells of feline immunodeficiency virus-infected cats
J. Gen. Virol.,
September 1, 2004;
85(9):
2585 - 2589.
[Abstract]
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M. Lichterfeld, X. G. Yu, M. T. Waring, S. K. Mui, M. N. Johnston, D. Cohen, M. M. Addo, J. Zaunders, G. Alter, E. Pae, et al.
HIV-1-specific cytotoxicity is preferentially mediated by a subset of CD8+ T cells producing both interferon-{gamma} and tumor necrosis factor-{alpha}
Blood,
July 15, 2004;
104(2):
487 - 494.
[Abstract]
[Full Text]
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L. I. Sakkas, G. Koussidis, E. Avgerinos, J. Gaughan, and C. D. Platsoucas
Decreased Expression of the CD3{zeta} Chain in T Cells Infiltrating the Synovial Membrane of Patients with Osteoarthritis
Clin. Vaccine Immunol.,
January 1, 2004;
11(1):
195 - 202.
[Abstract]
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O. O. Yang, P. T. N. Sarkis, A. Ali, J. D. Harlow, C. Brander, S. A. Kalams, and B. D. Walker
Determinants of HIV-1 Mutational Escape From Cytotoxic T Lymphocytes
J. Exp. Med.,
May 19, 2003;
197(10):
1365 - 1375.
[Abstract]
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E. J. Wherry, J. N. Blattman, K. Murali-Krishna, R. van der Most, and R. Ahmed
Viral Persistence Alters CD8 T-Cell Immunodominance and Tissue Distribution and Results in Distinct Stages of Functional Impairment
J. Virol.,
April 15, 2003;
77(8):
4911 - 4927.
[Abstract]
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D. Zhang, P. Shankar, Z. Xu, B. Harnisch, G. Chen, C. Lange, S. J. Lee, H. Valdez, M. M. Lederman, and J. Lieberman
Most antiviral CD8 T cells during chronic viral infection do not express high levels of perforin and are not directly cytotoxic
Blood,
January 1, 2003;
101(1):
226 - 235.
[Abstract]
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B. M. Badran, S. M. Wolinsky, A. Burny, and K. E. Willard-Gallo
Identification of Three NFAT Binding Motifs in the 5'-Upstream Region of the Human CD3gamma Gene That Differentially Bind NFATc1, NFATc2, and NF-kappa B p50
J. Biol. Chem.,
November 27, 2002;
277(49):
47136 - 47148.
[Abstract]
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E. Wieckowski, G.-Q. Wang, B. R. Gastman, L. A. Goldstein, and H. Rabinowich
Granzyme B-mediated Degradation of T-Cell Receptor {zeta} Chain
Cancer Res.,
September 1, 2002;
62(17):
4884 - 4889.
[Abstract]
[Full Text]
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M. E. Keir, M. G. Rosenberg, J. K. Sandberg, K. A. Jordan, A. Wiznia, D. F. Nixon, C. A. Stoddart, and J. M. McCune
Generation of CD3+CD8low Thymocytes in the HIV Type 1-Infected Thymus
J. Immunol.,
September 1, 2002;
169(5):
2788 - 2796.
[Abstract]
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H. Liu, S. Andreansky, G. Diaz, T. Hogg, and P. C. Doherty
Reduced Functional Capacity of CD8+ T Cells Expanded by Post-Exposure Vaccination of {gamma}-Herpesvirus-Infected CD4-Deficient Mice
J. Immunol.,
April 1, 2002;
168(7):
3477 - 3483.
[Abstract]
[Full Text]
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S. Kostense, K. Vandenberghe, J. Joling, D. Van Baarle, N. Nanlohy, E. Manting, and F. Miedema
Persistent numbers of tetramer+ CD8+ T cells, but loss of interferon-gamma + HIV-specific T cells during progression to AIDS
Blood,
April 1, 2002;
99(7):
2505 - 2511.
[Abstract]
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J. Lieberman, P. Shankar, N. Manjunath, and J. Andersson
Dressed to kill? A review of why antiviral CD8 T lymphocytes fail to prevent progressive immunodeficiency in HIV-1 infection
Blood,
September 15, 2001;
98(6):
1667 - 1677.
[Abstract]
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G. Chen, P. Shankar, C. Lange, H. Valdez, P. R. Skolnik, L. Wu, N. Manjunath, and J. Lieberman
CD8 T cells specific for human immunodeficiency virus, Epstein-Barr virus, and cytomegalovirus lack molecules for homing to lymphoid sites of infection
Blood,
July 1, 2001;
98(1):
156 - 164.
[Abstract]
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E. Y. Woo, C. S. Chu, T. J. Goletz, K. Schlienger, H. Yeh, G. Coukos, S. C. Rubin, L. R. Kaiser, and C. H. June
Regulatory CD4+CD25+ T Cells in Tumors from Patients with Early-Stage Non-Small Cell Lung Cancer and Late-Stage Ovarian Cancer
Cancer Res.,
June 1, 2001;
61(12):
4766 - 4772.
[Abstract]
[Full Text]
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T. U. Vogel, T. M. Allen, J. D. Altman, and D. I. Watkins
Functional Impairment of Simian Immunodeficiency Virus-Specific CD8+ T Cells during the Chronic Phase of Infection
J. Virol.,
March 1, 2001;
75(5):
2458 - 2461.
[Abstract]
[Full Text]
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T. J. Sayers, A. D. Brooks, J. M. Ward, T. Hoshino, W. E. Bere, G. W. Wiegand, J. M. Kelley, and M. J. Smyth
The Restricted Expression of Granzyme M in Human Lymphocytes
J. Immunol.,
January 15, 2001;
166(2):
765 - 771.
[Abstract]
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U. Kumaraguru, I. A. Davis, S. Deshpande, S. S. Tevethia, and B. T. Rouse
Lymphotoxin {{alpha}}-/- Mice Develop Functionally Impaired CD8+ T Cell Responses and Fail to Contain Virus Infection of the Central Nervous System
J. Immunol.,
January 15, 2001;
166(2):
1066 - 1074.
[Abstract]
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M. A. Ostrowski, S. J. Justement, L. Ehler, S. B. Mizell, S. Lui, J. Mican, B. D. Walker, E. K. Thomas, R. Seder, and A. S. Fauci
The Role of CD4+ T Cell Help and CD40 Ligand in the In Vitro Expansion of HIV-1-Specific Memory Cytotoxic CD8+ T Cell Responses
J. Immunol.,
December 1, 2000;
165(11):
6133 - 6141.
[Abstract]
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P. Shankar, M. Russo, B. Harnisch, M. Patterson, P. Skolnik, and J. Lieberman
Impaired function of circulating HIV-specific CD8+ T cells in chronic human immunodeficiency virus infection
Blood,
November 1, 2000;
96(9):
3094 - 3101.
[Abstract]
[Full Text]
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L. A. Trimble, P. Shankar, M. Patterson, J. P. Daily, and J. Lieberman
Human Immunodeficiency Virus-Specific Circulating CD8 T Lymphocytes Have Down-Modulated CD3zeta and CD28, Key Signaling Molecules for T-Cell Activation
J. Virol.,
August 15, 2000;
74(16):
7320 - 7330.
[Abstract]
[Full Text]
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L. A. Trimble, L. W. Kam, R. S. Friedman, Z. Xu, and J. Lieberman
CD3zeta and CD28 down-modulation on CD8 T cells during viral infection
Blood,
August 1, 2000;
96(3):
1021 - 1029.
[Abstract]
[Full Text]
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S. I. Gringhuis, A. Leow, E. A. M. Papendrecht-van der Voort, P. H. J. Remans, F. C. Breedveld, and C. L. Verweij
Displacement of Linker for Activation of T Cells from the Plasma Membrane Due to Redox Balance Alterations Results in Hyporesponsiveness of Synovial Fluid T Lymphocytes in Rheumatoid Arthritis
J. Immunol.,
February 15, 2000;
164(4):
2170 - 2179.
[Abstract]
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N. Manjunath, P. Shankar, B. Stockton, P. D. Dubey, J. Lieberman, and U. H. von Andrian
A transgenic mouse model to analyze CD8+ effector T cell differentiation in vivo
PNAS,
November 23, 1999;
96(24):
13932 - 13937.
[Abstract]
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P. Shankar, Z. Xu, and J. Lieberman
Viral-Specific Cytotoxic T Lymphocytes Lyse Human Immunodeficiency Virus-Infected Primary T Lymphocytes by the Granule Exocytosis Pathway
Blood,
November 1, 1999;
94(9):
3084 - 3093.
[Abstract]
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M. Dalod, M. Dupuis, J.-C. Deschemin, D. Sicard, D. Salmon, J.-F. Delfraissy, A. Venet, M. Sinet, and J.-G. Guillet
Broad, Intense Anti-Human Immunodeficiency Virus (HIV) Ex Vivo CD8+ Responses in HIV Type 1-Infected Patients: Comparison with Anti-Epstein-Barr Virus Responses and Changes during Antiretroviral Therapy
J. Virol.,
September 1, 1999;
73(9):
7108 - 7116.
[Abstract]
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I. Segura, C. Delmelle-Wibaut, M. Janssens, Y. Cleuter, A. van den Broeke, R. Kettmann, and K. E. Willard-Gallo
Human Immunodeficiency Virus Type 2 Produces a Defect in CD3-gamma Gene Transcripts Similar to That Observed for Human Immunodeficiency Virus Type 1
J. Virol.,
June 1, 1999;
73(6):
5207 - 5213.
[Abstract]
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B. R. Gastman, D. E. Johnson, T. L. Whiteside, and H. Rabinowich
Caspase-mediated Degradation of T-Cell Receptor {{zeta}}-Chain
Cancer Res.,
April 1, 1999;
59(7):
1422 - 1427.
[Abstract]
[Full Text]
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Abstract
Introduction
Abstract