|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
Blood, Vol. 93 No. 3 (February 1), 1999:
pp. 952-962
By
From the Research Center, Maisonneuve-Rosemont Hospital, Montreal,
Quebec, Canada; and The Jackson Laboratory, Bar Harbor, ME.
The immunodominance effect, whereby the presence of immunodominant
epitopes prevents recognition of nondominant determinants presented on
the same antigen-presenting cell (APC) considerably restricts the
repertoire of cytotoxic T lymphocyte (CTL) responses. To elucidate the
molecular basis of the immunodominance effect, we compared the
interactions of a dominant (B6dom1) and a nondominant
epitope (H-Y) with their restricting class I molecule
(H2-Db), and their ability to trigger cognate CTLs. We
found that B6dom1/Db complexes behaved as
optimal T-cell receptor (TCR) ligands and triggered a more rapid in
vivo expansion of cognate CTLs than H-Y/Db complexes. The
superiority of the dominant epitope was explained by its high cell
surface density (1,012 copies/cell for B6dom1 v 10 copies/cell for H-Y) and its optimal affinity for cognate TCRs. Based
on these results, we conclude that dominant class I-associated
epitopes are those that have optimal ability to trigger TCR signals in
CTLs. We propose that the rapid expansion of CTLs specific for dominant
antigens should enable them to compete more successfully than other
CTLs for occupancy of the APC surface.
WHEN CONFRONTED with numerous peptides
presented in the context of self-major histocompatibility complex
(MHC), T cells usually respond only to a limited number of peptide
epitopes.1,2 The immunogenicity of such peptides is
determined by four parameters: (1) the rate of processing (proteolysis
and transport) of peptide epitopes, (2) their MHC binding affinity, (3)
the presence of specific T-cell precursors, and (4) the suppression of
T-cell responses to nondominant peptides by dominant epitopes
(immunodominance effect).3-15 The immunodominance effect
considerably restricts the repertoire of T-cell effectors. Indeed,
several peptides that are adequately presented on antigen-presenting
cells (APCs) are said to be nondominant because they elicit T-cell
responses when they are presented alone, but are neglected when they
are presented in conjunction with other peptides. Immunodominance has
been found to regulate cytotoxic T lymphocyte (CTL) responses to
viruses,16,17 bacteria,18 tumor
antigens,19-21 and minor histocompatibility antigens
(MiHAs).22-30 Based on detailed studies of in
vivo and in vitro CTL responses toward MiHAs, it appears that only a
very small proportion of epitopes, probably less than 10%, are
dominant.22-28 A priori, immunodominance may not appear
advantageous, as it signifies that by focusing exclusively on one or a
few epitopes, the immune system places all its eggs in the same (or a
few) basket(s). Theoretically, this should increase the risk that
pathogens or tumor cells can escape from
immunosurveillance.31 Therefore, it is of great importance
to decipher the rules that govern immunodominance to understand why the
repertoire of T-cell responses is restricted to only a few determinants
when confronted with numerous immunogenic epitopes and what are the
implications of this restriction.
When immunized against C57BL/6 cells, C3H.SW mice recognize a small set
of class I-associated dominant MiHAs collectively called
B6dom.32,33 To investigate the mechanisms of
dominance, we compared immune responses towards B6dom and
H-Y antigens because, in H2b mice, these MiHAs lie at
opposite ends on the dominance scale. Indeed, H-Y is always nondominant
when presented with one or numerous autosomal MiHAs, whereas
B6dom are dominant antigens when presented with other
MiHAs.32,34 Thus, when C3H.SW female mice were primed with
C57BL/6 male cells, they generated anti-B6dom CTLs, but
failed to respond to H-Y even though (1) C3H.SW female mice could
respond to H-Y when it was presented alone (on C3H.SW male cells), and
(2) C57BL/6 male cells express H-Y MiHA.32 B6dom did not suppress anti-H-Y responses by acting as a
T-cell receptor (TCR) antagonist for anti-H-Y CTLs because
B6dom and H-Y are not cross-reactive at the TCR level.
Importantly, dominance was not seen when mice (C3H.SW female) were
primed with the dominant and nondominant antigens on separate APCs (ie,
a mixture of C3H.SW male cells + C57BL/6 female
cells).32 These results indicated that dominance results
from competition for the APC surface between anti-B6dom and
anti-H-Y CTLs.2
Taking advantage of the recent elucidation of the sequence of the H-Y
and B6dom1 epitopes,33,35 both presented by
H2-Db, we evaluated the molecular basis of the
immunodominance effect. The results presented herein show that compared
with H2-Db/H-Y complexes,
H2-Db/B6dom1 complexes are more abundant at the
surface of APCs, likely interact with optimal affinity with their
specific TCR, and trigger a more rapid expansion of cognate CTLs.
Coupled with previous work,32 these findings provide strong
evidence that because of their rapid expansion, CTLs directed towards
immunodominant antigens occupy the surface of APCs and thereby prevent
the interaction of antinondominant CTLs with these same APCs. In this
way, CTL responses are focused on those antigens which are the most
effective at triggering T-cell activation.
Mice.
Mice from the Jackson Laboratory (Bar Harbor, ME) were used between 6 and 16 weeks of age. They were maintained on acidified drinking water
and under normal housing conditions according to the standards of the
Canadian Committee for Animal Protection.
Cell lines.
The T2Db cell line (kindly provided by Dr P. Cresswell,
Yale University, New Haven, CT) was created by transfection of T2 cells with the H2-Db gene.36 T2 is a human hybrid
lymphoblastoid cell line with a large deletion in the MHC class II
region, including genes for the TAP1/2 and LMP2/7 products. RMA-S
(H2b) is a TAP2 mutant cell line expressing very low
surface amounts of MHC class I molecules. SW10/B, an established
AAPDNRETF-specific CD8+ cell line was generated by priming
intraperitoneally (IP) C3H.SW mice with C57BL/6 spleen cells followed
by four cycles of in vitro restimulation of effector cells with C3H.SW
cells coated with synthetic AAPDNRETF peptide (Christianson GJ, Pion S,
Roopenian DC, Perreault C, unpublished observation, October 1997).
Synthetic peptides.
Peptides were synthesized by Chiron Technologies (Victoria, Australia).
AAPDNRETF (B6dom1) is an H2-Db-restricted
dominant MiHA present on the surface of C57BL/6 spleen cells.33 WMHHNMDLI (H-Y) is a male specific
H2-Db-restricted MiHA derived from the UTY
protein.35 Purity, as determined by reversed
phase-high-performance liquid chromatography (HPLC), was above 97%
for both synthetic peptides.
Extraction and HPLC fractionation of natural MiHA peptides.
Natural MiHA peptides were eluted from C57BL/6 male cells by acid
extraction in the presence of protease inhibitors (25 mmol/L iodoacetamide, 1 mmol/L aprotinine, 1 mmol/L phenylmethyl sulfonyl fluoride [PMSF]).32,37 Thus, 2 × 108
cells were suspended in 5 mL of citrate-phosphate buffer (0.131 mol/L
citric acid/0.066 mol/L Na2HPO4, pH 3.3) for 1 minute at room temperature and centrifuged. Under these experimental
conditions (pH < 3.4), the efficiency of peptide extraction is
CTL assays.
Standard 51Cr-release assays were performed as previously
described.32,38,39 Analysis of the expression of
B6dom1 by various strains of H2b mice and
quantification of natural AAPDNRETF epitopes expressed by C57BL/6 and
129 cells were performed with SW10/B effectors (see Fig 3). In all
other experiments, effectors were polyclonal CTLs obtained after a
single in vivo priming followed by a single in vitro mixed leukocyte
culture (MLC).32 Target cells were either concanavalin A
(Con A) blasts or T2Db cells that were either
untreated or preincubated with an exogenous source of peptides in the
form of HPLC fractions or synthetic peptides. In peptide sensitization
assays, target cells were incubated at 26°C overnight, then
sensitized with synthetic peptides or HPLC fractions for 90 minutes
before being used in CTL assays. Effectors were incubated with targets
for 3 hours in standard CTL assays and for 4 hours in peptide
sensitization assays. All tests were performed in triplicate.
Spontaneous release values varied from 5% to 20% of total release.
Interactions between H2-Db and MiHA peptides.
The binding affinity of WMHHNMDLI and AAPDNRETF for the Db
molecule was evaluated by fluorescence-activated cell sorting (FACS) analysis with anti-H2-Db antibody (Ab) (cat
no. 06114D; Cedarlane, Hornby, Canada) using T2Db and RMA-S cells, as previously
described.32 The anti-H2-Db Ab used recognizes
an epitope whose expression is not modified by the nature of the
specific peptide bound to Db molecules.40
Briefly, T2Db and RMA-S cells were sensitized with
different concentrations of synthetic peptides to stabilize surface
H2-Db expression. Afterwards, cells were stained with
anti-H2-Db Ab, washed, and analyzed by FACS. To evaluate
the half-life of H2-Db/peptide complexes, T2Db
cells were incubated for 12 hours in the presence of B6dom1
(10 Limiting dilution analysis (LDA) of CTL precursor frequencies.
Limiting numbers of responder spleen cells from C3H.SW female mice
primed either with C57BL/6 female (B6dom1+) or C3H.SW male
(H-Y+) splenocytes (20 × 106 cells
injected IP) were restimulated in vitro on days 5, 10, 15, or 20 postimmunization with 3 × 105 irradiated stimulator
cells in the presence of 2.5 or 20 U/mL of interleukin-2 (IL-2). After
9 days, cultures were evaluated in a standard 4-hour 51Cr
release assay. Wells were scored positive if 51Cr release
exceeded the spontaneous release by more than 3 SD. The frequency of
CTL precursors was determined by the Relative affinities of AAPDNRETF (B6dom1) and
WMHHNMDLI (H-Y) for Db.
To evaluate the binding affinity for Db molecules, we
compared the ability of synthetic B6dom1 and H-Y peptides
to upregulate Db expression on T2Db and RMA-S
cells. As they are deficient in TAP1/2 and LMP2/7 proteins (T2Db) or TAP2 (RMA-S), these cells express only low levels
of unstable Db molecules on the cell surface.36
However, when exogenous Db-binding peptides are added, they
stabilize "empty" Db molecules, thereby causing an
increased cell surface expression of this class I molecule that can be
measured by flow cytometry. Studies involving a large variety of
peptides have demonstrated that MHC stabilization assays can be taken
as a measure of the relative peptide affinity.4,5,7,13
Thus, both types of cells were incubated with titrated amounts of H-Y
and B6dom1 peptides and stained with an anti-Db
Ab. In three experiments with T2Db cells, the concentration
of H-Y required for half-maximal Db upregulation was one to
two logs greater than that of B6dom1. In the representative
example depicted in Fig 1B, the peptide concentrations required for similar Db expression were 2 × 10
Stability of Db/peptide complexes.
T2Db cells, precultured overnight at 26°C, were
incubated with B6dom1 or H-Y peptide. Peptides were used at
different molar concentrations selected to obtain an MFI of
Cell surface density of naturally processed B6dom1 and
H-Y epitopes.
Peptides associated with cell surface MHC molecules were obtained by
acid elution from C57BL/6 male splenocytes, fractionated by HPLC, and
their biologic activity was compared with that of synthetic peptides
(AAPDNRETF and WMHHNMDLI) in CTL sensitization assays using
T2Db targets with anti-H-Y- and
anti-B6dom1-specific effectors.32,37
Polyclonal anti-H-Y CTLs, obtained after a single in vivo priming and
in vitro restimulation of C3H.SW female cells with C3H.SW male cells,
were used for quantification of natural H-Y epitopes because such
effectors recognize a single peptide-Db
complex.43 B6dom1 activity was detected with an
AAPDNRETF-specific C3H.SW-derived CTL line (SW10/B). The retention
times of the natural B6dom1 and H-Y peptides were identical
to those of the synthetic peptides: 18 minutes for AAPDNRETF and 27 minutes for WMHHNMDLI (data not shown). As a control, peptides
extracted from C3H.SW female cells did not sensitize target cells to
lysis by anti-B6dom1 or anti-H-Y effectors (data not shown).
Relative avidity of CTL target cell recognition of B6dom1
and H-Y epitopes.
The avidity of CTL/APC interaction is the product of the cell surface
density of the peptide/MHC complex on the APC and the intrinsic
affinity between these complexes and their specific TCR. To compare the
relative avidity of target cell recognition by specific CTLs,
polyclonal anti-B6dom and anti-H-Y CTLs were tested in
cytotoxicity assays with female C3H.SW targets sensitized with graded
concentrations of synthetic B6dom1 and H-Y peptides. The
concentration of H-Y peptide necessary to sensitize targets for 50%
lysis was very low (10
In vivo expansion of anti-B6dom1 and anti-H-Y CTLs.
Epitope density and TCR affinity regulate the rate of expansion of
cognate CTLs.50-52 To evaluate the kinetics of the primary response, we monitored the frequencies of B6dom1- and
H-Y-specific CTLs at various time points after immunization using LDA.
This approach has been widely used to evaluate the kinetics of CTL
responses.53,54 Thus, C3H.SW female mice were primed with
C3H.SW male cells (H-Y+) or C57BL/6 female cells
(B6dom1+), their spleen cells were harvested on day 5, 10, 15, or 20, and cultured under limiting dilution conditions in
IL-2-supplemented medium with the same cell type as for priming. After
9 days, CTL activity was tested on T2Db targets coated with
optimal concentrations of synthetic B6dom1 or H-Y peptide.
Assays performed after culture in the presence of low concentrations of
IL-2 (2.5 U/mL) showed that the expansion of anti-B6dom1
CTLs was much more rapid than that of anti-H-Y CTLs
(Fig 5). Thus, on day 5, the mean frequency
of anti-B6dom1 CTL precursors was 20-fold greater than that
of anti-H-Y precursors. The difference was still significant on day 15 (7.5-fold) and disappeared on day 20. CTL precursor frequencies were
similar, however, when the culture medium was supplemented with high
concentrations of IL-2 (20 U/mL); in the latter case, anti-H-Y and
anti-B6dom1 precursor frequencies reached 2 × 10-5 on day 20 (data not shown). Thus, unless large amounts
of IL-2 were added, the proliferation rate of anti-B6dom1
CTLs was higher than that of anti-H-Y CTLs. The fact that under these
assay conditions H-Y-specific CTLs were more dependent on the supply
of exogenous IL-2 than B6dom1-specific CTLs is consistent
with previous evidence that in vivo expansion of anti-H-Y CTLs
requires CD4 help, whereas expansion of anti-B6dom1 CTLs
does not.33,55
Is B6dom1 expressed by cells with a different genetic
background always a dominant epitope?
The results presented above strongly suggest that the high cell surface
density of B6dom1 has a determining influence on the fact
that this antigen is a dominant MiHA recognized by C3H.SW mice when
primed against C57BL/6 cells. Thus, it is logical to assume that if the
expression of the B6dom1 epitope was decreased below a
certain threshold, B6dom1 would lose its dominant status.
The next series of experiments were designed to test this possibility
and to evaluate what could be the expression threshold required for
B6dom1 to be a dominant MiHA.
B6dom1/Db complexes are optimal CTL ligands.
The results presented herein (summarized in
Table 1) disclose major differences between
the nondominant and the dominant antigens recognized by C3H.SW-derived
CTLs on C57BL/6 cells: H-Y/Db complexes show a low cell
surface density, but are recognized by TCRs with very high relative
affinity, whereas B6dom1/Db complexes are more
abundant and interact with lower affinity TCRs.
How can expression of B6dom1 inhibit anti-H-Y CTL
responses?
Previous analyses of CTL responses toward B6dom1 and H-Y
showed that the most critical characteristic of the immunodominance
effect is that "suppression" of T-cell responses to nondominant
epitopes by dominant epitopes is observed only when both types of
determinants are presented on the same APC.32,34 This
observation indicates that differential generation of T-cell help
cannot be responsible for B6dom1 immunodominance over
H-Y/Db. Indeed, help from other T cells, particularly from
the CD4+ subset, is available to all CD8+ CTLs
that recognize epitopes presented on the same APC, irrespective of the
specificity of helper cells and CTLs.55,68-70 Thus, after immunization with C57BL/6 male cells, anti-B6dom1 and
anti-H-Y CTLs receive the same help because both MiHAs are presented
on the same APC. Therefore, the fact that dominance takes place only
when the dominant and the nondominant epitopes are presented on the
same APC suggests that the immunodominance effect results from a
competition for the APC surface.
What is the raison d'être of the immunodominance effect?
Is it a good strategy for the immune system to restrict the repertoire
of CTL responses to a few dominant epitopes and hence to suppress
responses to other nondominant epitopes expressed by APCs? Analysis of
CTL responses to B6dom1 and H-Y shows that the
immunodominance effect is not a stochastic process. Indeed, based on
the characteristics of B6dom1, we conclude that dominant
epitopes are those, which have optimal ability to trigger TCR signals
in CTLs. Thus, whether the critical final event is competition for the
APC surface + cytokines or APC killing, the dominance effect can serve
two important purposes. First, considering that naive T cells require
approximately 20 hours of sustained signaling to be committed to
proliferation78 and that APCs disappear less than 48 hours
after interaction with cognate T cells in vivo,79 the
dominance effect may help to minimize the time required to mount a
protective immune response by devoting the APC surface to CTLs specific
for the best TCR ligands during the brief period of priming. This could
be extremely important considering how critical time limitations are
for CTL to mediate early control of a microbial infection in
vivo.80,81 Secondly, taking into account that TCRs are
degenerate receptors and that T lymphocytes responding to
nonself-antigens can cross-react with self-peptides,4,82,83
restricting the repertoire of T-cell responses may decrease the risk of
autoimmunity. Thus, the immunodominance phenomenon may, in fact,
represent an astute "low risk high efficiency" strategy for the
immune system: restricting the diversity of the immune response limits
the potential for autoimmune recognition, while focusing on the best
epitopes confers good chances to rapidly eliminate pathogens.
Submitted April 30, 1998; accepted September 24, 1998.
Supported by the National Cancer Institute of Canada (C.P.) and the
National Institute of Allergy and Infectious Diseases (D.C.R.).
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.
Address reprint requests to Claude Perreault, MD, Research
Center, Maisonneuve-Rosemont Hospital, 5415 de l'Assomption Blvd,
Montreal, Quebec, Canada H1T 2M4; e-mail: c.perreault{at}videotron.ca.
1.
Sercarz EE, Lehmann PV, Ametani A, Benichou G, Miller A, Moudgil K:
Dominance and crypticity of T cell antigenic determinants.
Annu Rev Immunol
11:729, 1993[Medline]
[Order article via Infotrieve]
2.
Perreault C, Roy DC, Fortin C:
Immunodominant minor histocompatibility antigens: The major ones.
Immunol Today
19:69, 1998[Medline]
[Order article via Infotrieve]
3.
Vitiello A, Yuan L, Chesnut RW, Sidney J, Southwood S, Farness P, Jackson MR, Peterson PA, Sette A:
Immunodominance analysis of CTL responses to influenza PR8 virus reveals two new dominant and subdominant Kb-restricted epitopes.
J Immunol
157:5555, 1996[Abstract]
4.
Deng Y, Yewdell JW, Eisenlohr LC, Bennink JR:
MHC affinity, peptide liberation, T cell repertoire, and immunodominance all contribute to the paucity of MHC class I-restricted peptides recognized by antiviral CTL.
J Immunol
158:1507, 1997[Abstract]
5.
Chen W, Khilko S, Fecondo J, Margulies DH, McCluskey J:
Determinant selection of major histocompatibility complex class I-restricted antigenic peptides is explained by class I-peptide affinity and is strongly influenced by nondominant anchor residues.
J Exp Med
180:1471, 1994
6.
Daly K, Nguyen P, Woodland DL, Blackman MA:
Immunodominance of major histocompatibility complex class I-restricted influenza virus epitopes can be influenced by the T-cell receptor repertoire.
J Virol
69:7416, 1995[Abstract]
7.
Oukka M, Riche N, Kosmatopoulos K:
A nonimmunodominant nucleoprotein-derived peptide is presented by influenza A virus-infected H-2b cells.
J Immunol
152:4843, 1994[Abstract]
8.
Ressing ME, Sette A, Brandt RM, Ruppert J, Wentworth PA, Hartman M, Oseroff C, Grey HM, Melief CJ, Kast WM:
Human CTL epitopes encoded by human papillomavirus type 16 E6 and E7 identified through in vivo and in vitro immunogenicity studies of HLA-A*0201-binding peptides.
J Immunol
154:5934, 1995[Abstract]
9.
Connolly JM:
The peptide p2Ca is immunodominant in allorecognition of Ld by b chain variable region Vb8+ but not Vb8
10.
Dong T, Boyd D, Rosenberg W, Alp N, Takiguchi M, McMichael A, Rowland-Jones S:
An HLA-B35-restricted epitope modified at an anchor residue results in an antagonist peptide.
Eur J Immunol
26:335, 1996[Medline]
[Order article via Infotrieve]
11.
Kageyama S, Tsomides TJ, Sykulev Y, Eisen HN:
Variations in the number of peptide-MHC class I complexes required to activate cytotoxic T cell responses.
J Immunol
154:567, 1995[Abstract]
12.
Levitsky V, Zhang QJ, Levitskaya J, Masucci MG:
The life span of major histocompatibility complex-peptide complexes influences the efficiency of presentation and immunogenicity of two class I-restricted cytotoxic T lymphocyte epitopes in the Epstein-Barr virus nuclear antigen 4.
J Exp Med
183:915, 1996
13.
van der Burg SH, Visseren MJ, Brandt RM, Kast WM, Melief CJ:
Immunogenicity of peptides bound to MHC class I molecules depends on the MHC-peptide complex stability.
J Immunol
156:3308, 1996[Abstract]
14.
Sijts AJ, Villanueva MS, Pamer EG:
CTL epitope generation is tightly linked to cellular proteolysis of a Listeria monocytogenes antigen.
J Immunol
156:1497, 1996[Abstract]
15.
Moudgil KD, Sekiguchi D, Kim SY, Sercarz EE:
Immunodominance is independent of structural constraints. Each region within hen eggwhite lysozyme is potentially available upon processing of native antigen.
J Immunol
159:2574, 1997[Abstract]
16.
Silins SL, Cross SM, Elliott SL, Pye SJ, Burrows SR, Burrows JM, Moss DJ, Argaet VP, Misko IS:
Development of Epstein-Barr virus-specific memory T cell receptor clonotypes in acute infectious mononucleosis.
J Exp Med
184:1815, 1996
17.
Steven NM, Leese AM, Annels NE, Lee SP, Rickinson AB:
Epitope focusing in the primary cytotoxic T cell response to Epstein-Barr virus and its relationship to T cell memory.
J Exp Med
184:1801, 1996
18.
Ugrinovic S, Mertz A, Wu P, Braun J, Sieper J:
A single nonamer from the Yersinia 60-kDa heat shock protein is the target of HLA-B27-restricted CTL response in Yersinia-induced reactive arthritis.
J Immunol
159:5715, 1997[Abstract]
19.
Dudley ME, Roopenian DC:
Loss of a unique tumor antigen by cytotoxic T lymphocyte immunoselection from a 3-methylcholanthrene-induced mouse sarcoma reveals secondary unique and shared antigens.
J Exp Med
184:441, 1996
20.
Huang AY, Gulden PH, Woods AS, Thomas MC, Tong CD, Wang W, Engelhard VH, Pasternack G, Cotter R, Hunt D, Pardoll DM, Jaffee EM:
The immunodominant major histocompatibility complex class I-restricted antigen of a murine colon tumor derives from an endogenous retroviral gene product.
Proc Natl Acad Sci USA
93:9730, 1996
21.
Johnston JV, Malacko AR, Mizuno MT, McGowan P, Hellstrom I, Hellstrom KE, Marquardt H, Chen L:
B7-CD28 costimulation unveils the hierarchy of tumor epitopes recognized by major histocompatibility complex class I-restricted CD8+ cytolytic T lymphocytes.
J Exp Med
183:791, 1996
22.
Wettstein PJ, Bailey DW:
Immunodominance in the immune response to "multiple" histocompatibility antigens.
Immunogenetics
16:47, 1982[Medline]
[Order article via Infotrieve]
23.
Wettstein PJ:
Immunodominance in the T-cell response to multiple non-H-2 histocompatibility antigens. II. Observation of a hierarchy among dominant antigens.
Immunogenetics
24:24, 1986[Medline]
[Order article via Infotrieve]
24.
Korngold R, Wettstein PJ:
Immunodominance in the graft-vs-host disease T cell response to minor histocompatibility antigens.
J Immunol
145:4079, 1990[Abstract]
25.
Yin L, Poirier G, Neth O, Hsuan JJ, Totty NF, Stauss HJ:
Few peptides dominate cytotoxic T lymphocyte responses to single and multiple minor histocompatibility antigens.
Int Immunol
5:1003, 1993
26.
Tremblay N, Fontaine P, Perreault C:
T lymphocyte responses to multiple minor histocompatibility antigens generate both self-major histocompatibility complex-restricted and cross-reactive cytotoxic T lymphocytes.
Transplantation
58:59, 1994[Medline]
[Order article via Infotrieve]
27.
Brochu S, Baron C, Hetu F, Roy DC, Perreault C:
Oligoclonal expansion of CTLs directed against a restricted number of dominant minor histocompatibility antigens in hemopoietic chimeras.
J Immunol
155:5104, 1995[Abstract] |
Top
Abstract
Introduction
95%.
7 mol/L) or H-Y (10
MFImin, where
MFIexp is the fluorescence intensity of cells incubated
with one of the synthetic peptides and MFImin is the
fluorescence intensity of cells that had been pulsed with medium alone
before labeling with the anti-H2-Db Ab.
2 minimization procedure.
) or 1.6 × 107 (
)
C3H.SW male cells, respectively. Also evaluated were the activities of
extracts from 8 × 106, 1.2 × 107, or 1.6 × 107 C57BL/6 male cells and 4 × 106, 8 × 106, or 1.2 × 107 129 male cells. The number
of epitope copies per cell was established at 824, 903, and 1,200, respectively for C57BL/6, and at 112, 126, and 107 copies for 129 cells
(data not shown). One representative experiment of three is shown. (C)
The activity of natural B6dom1 peptide extracted from
8 × 106 (C57BL/6J × C3H.HeJ)F1
cells is plotted on a dose response curve depicting the activity of
graded concentrations of synthetic B6dom1 peptide mixed
with competitor peptides extracted from 8 × 106 C3H.SW
male cells, respectively. One representative experiment of two is
shown. Targets were T2Db cells. E:T ratio was 5:1 for
anti-B6dom1 effectors (SW10/B cell line) and 50:1 for
anti-H-Y effectors.
), control
YSNENMDAM peptide (
), or culture medium alone (
). (B) LP-derived
anti-C57BL/6 CTLs do not kill T2Db targets coated with
B6dom1 peptide. E:T ratio was 50:1 (closed bar) or 25:1
(open bar). (C) B6dom1-specific CTLs (SW10/B cell line)
kill 129 Con A blasts. (D) C3H.SW-derived anti-129 CTLs do not kill
C3H.SW Con A blast targets coated with optimal concentration of
B6dom1 peptide (AAPDNRETF; 10