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HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY
From the Institute for Advanced Medical Research and
the Department of Internal Medicine, Keio University School of
Medicine, Tokyo; the Department of Internal Medicine, Tokyo Electric
Power Company Hospital; the Department of Microbiology, Kitasato
University School of Medicine, Sagamihara; and the Institute of Medical
Science, St Marianna University School of Medicine, Kawasaki, Japan.
It was recently reported that autoreactive CD4+ T cells
to glycoprotein IIb-IIIa (GPIIb-IIIa) mediate antiplatelet autoantibody production in patients with immune thrombocytopenic purpura (ITP). To
further examine the antigenic specificity of the GPIIb-IIIa-reactive T
cells, 6 recombinant fragments encoding different portions of GPIIb Chronic immune thrombocytopenic purpura (ITP) is an
autoimmune disease characterized by increased platelet clearance caused by antiplatelet autoantibodies.1,2 These antibodies bind to circulating platelets, resulting in platelet destruction by the
reticuloendothelial system. The major target of the antiplatelet autoantibodies is platelet membrane glycoprotein IIb-IIIa
(GPIIb-IIIa),3-5 also designated
Our previous study demonstrated that GPIIb-IIIa-reactive T cells
respond to chemically modified GPIIb-IIIa and recombinant GPIIb-IIIa
fragments expressed in bacteria, but not to GPIIb-IIIa in its native
form.10 One possible explanation for this finding is that
autoreactive T cells recognize "cryptic" epitopes on GPIIb-IIIa that are not produced from native GPIIb-IIIa by the normal processing pathway. However, the precise locations of these cryptic epitopes have
not been reported. T-cell epitope mapping on GPIIb-IIIa is potentially
useful for detecting foreign cross-reactive proteins that elicit
autoantibody responses to GPIIb-IIIa11 and for developing therapeutic strategies that suppress harmful T-cell responses in
patients with ITP.12 In this study, a series of
recombinant fragments encompassing different portions of GPIIb Patients and controls
Control T cells were obtained from 10 healthy donors (4 men, 6 women)
who had no history of ITP and showed a T-cell proliferative response to
trypsin-digested GPIIb-IIIa. The mean age at examination was 36.7 years
(range, 23-56 years). All healthy controls had normal platelet counts
and were negative for anti-GPIIb-IIIa antibodies in plasma and
platelet eluates.
Human leukocyte antigen (HLA)-DRB1, -DQB1, and -DPB1 alleles were
determined for all patients and controls, using polymerase chain
reaction (PCR) followed by analysis of restriction fragment length
polymorphisms.13,14 Written informed consent approved by
the Institutional Review Board guidelines was granted by all study participants.
GPIIb-IIIa preparations for T-cell stimulation
Seven different portions of GPIIb Detection of anti-GPIIb-IIIa antibodies The level of immunoglobulin G (IgG) anti-GPIIb-IIIa antibodies in plasma, platelet eluates, and culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA) using affinity-purified GPIIb-IIIa as an antigen, as described elsewhere.5,10 All samples were tested in duplicate, and the results were calculated as the duplicate mean. Cutoff values for plasma and platelet eluates were considered the mean plus 3 × SD of 20 samples from healthy donors.GPIIb-IIIa-reactive T-cell lines GPIIb-IIIa-reactive T-cell lines were generated from patients with ITP using a previously described method17 with some modifications. Briefly, peripheral blood mononuclear cells (PBMCs) were isolated from heparinized venous blood using Lymphoprep (Nycomed Pharma AS, Oslo, Norway) density gradient centrifugation and were cultured in RPMI 1640 containing 8% pooled human AB serum, 2 mM L-glutamine, 50 U/mL penicillin, and 50 mg/mL streptomycin in the presence of trypsin-digested, platelet-derived GPIIb-IIIa (5 µg/mL) in a humidified atmosphere of 5% CO2 at 37°C. On day 3, 20 U/mL interleukin-2 (IL-2) (Life Technologies, Grand Island, NY) was added to the cultures. Cells were restimulated with trypsin-digested GPIIb-IIIa and IL-2 (50 U/mL) and irradiated (30 Gy) autologous PBMCs in fresh medium on day 10. Seven days after the second stimulation, T-cell blasts were cloned by limiting dilution at 1 to 100 cells/well using round-bottomed, 96-well plates in the presence of trypsin-digested GPIIb-IIIa, IL-2, and irradiated PBMCs. Wells that contained growing cells were selected, and these cells were expanded by repeated stimulation with trypsin-digested GPIIb-IIIa, IL-2, and autologous Epstein-Barr virus-transformed lymphoblastoid B cells irradiated at 100 Gy. The specificity of each T-cell line was assessed by antigen-induced T-cell proliferation assays, and T-cell lines that proliferated in response to trypsin-digested GPIIb-IIIa, but not to mock-treated PBS containing trypsin alone, were selected as GPIIb-IIIa-specific T-cell lines. Cell surface expression of CD4 and CD8 was examined by flow cytometry using fluorescein isothiocyanate-conjugated monoclonal antibodies (mAbs) against CD4 and CD8 (Becton Dickinson, San Jose, CA).T-cell proliferation assay The antigenic specificity of T cells was determined by antigen-induced T-cell proliferation.17,18 PBMCs were cultured in the presence or absence of antigen for 7 days unless otherwise indicated. GPIIb-IIIa-reactive T-cell lines were cultured with irradiated autologous lymphoblastoid B cells in the presence or absence of antigen for 3 days. After a final 16-hour incubation with 0.5 µCi/well of 3H-thymidine, the cells were harvested, and 3H-thymidine incorporation was determined in a TopCount microplate scintillation counter (Packard, Meriden, CT). Antigens were used at a concentration of 5 µg/mL and included native GPIIb-IIIa, trypsin-digested GPIIb-IIIa, mock-treated PBS, GST, tetanus toxoid (List Biological Laboratories, Campbell, CA), and individual recombinant GPIIb-IIIa fragments. All cultures were prepared in triplicate, and all values represent the mean of triplicate determinations. For bulk PBMC cultures, cpm was calculated by
subtracting the cpm value obtained in cultures incubated without
antigen from those obtained in cultures with antigen. Antigen-specific
T-cell proliferation in response to each recombinant GPIIb-IIIa
fragment was expressed as a stimulation index, which was calculated as the cpm incorporated into cultures with recombinant GPIIb-IIIa fragment divided by the cpm incorporated into cultures with GST. A
positive response was defined as having a stimulation index greater
than 3. Standard deviations were less than 20% of the mean or less
than 100 cpm, unless indicated otherwise. To examine the inhibitory
effects of anti-HLA class II mAb on antigen-specific T-cell
proliferation, mAbs were added at the start of the
cultures.10 Anti-HLA-DR (L243; IgG2a), anti-HLA-DQ (1a3;
IgG2a), anti-HLA-DP (B7/21; IgG3), and isotype-matched control mAbs
(Leinco Technologies, Ballwin, MO) were dialyzed against PBS and used
at a final concentration of 1 µg/mL.
In vitro assay for anti-GPIIb-IIIa antibody production An in vitro assay to analyze the antigen-induced anti-GPIIb-IIIa antibody synthesis in PBMC cultures or in cultures of GPIIb-IIIa-reactive T-cell lines and autologous peripheral blood B cells was carried out as described.10,19 Briefly, PBMCs (5 × 105/well) or GPIIb-IIIa-reactive T cells (2 × 105) plus autologous peripheral blood B cells (105) were cultured in complete medium with or without antigen in the presence of pokeweed mitogen (1 µg/mL) for 10 days. Individual recombinant GPIIb-IIIa fragments and GST were used at 5 µg/mL as antigens. In some experiments, anti-interferon (IFN-) (25718.11; IgG2a), anti-IL-4 (34019.111; IgG2b), or
anti-IL-6 (6708.111; IgG1) mAb (Genzyme Techne, Cambridge, MA) were
added at the initiation of the culture. IgG anti-GPIIb-IIIa antibody
levels in undiluted culture supernatants were measured by ELISA using
purified GPIIb-IIIa as an antigen source, as described above. All
cultures were prepared in duplicate, and anti-GPIIb-IIIa antibody
results represent the mean of duplicate values. Significant
anti-GPIIb-IIIa antibody production in response to antigenic
stimulation with recombinant GPIIb-IIIa fragments was defined as having
both a value greater than 2 for the anti-GPIIb-IIIa antibody levels in
cultures with a recombinant GPIIb-IIIa fragment divided by the
anti-GPIIb-IIIa antibody levels in cultures with GST and an increase
in OD450 (optical density) greater than 0.1 associated with
antigenic stimulation. In some experiments, anti-GPIIb-IIIa antibodies
produced in culture supernatants were absorbed by incubation with
platelets, erythrocytes, or PBMCs obtained from 2 independent healthy
donors, as described elsewhere.10 Standard deviations were
less than 20% of the mean or less than 0.01 (OD450),
unless indicated otherwise.
Cytokine production assay For the determination of cytokine profiles in individual GPIIb-IIIa-reactive T-cell lines, T cells were cultured with phytohemagglutinin (1 µg/mL) and an anti-CD3 mAb (OKT3; 30 ng/mL) for 48 hours, and the supernatants were collected and stored at 80°C
until analysis. The levels of human IFN-, IL-4, and IL-6 in the
culture supernatants were measured in duplicate using ELISA kits
(BioSource International, Camarillo, CA) according to the
manufacturer's instructions.
Statistical analysis All comparisons between the 2 groups were tested for statistical significance using the Fisher 2-tailed exact test or the Student t test. Correlation coefficient (r) was determined using a single regression model.
Expression and purification of recombinant GPIIb  18-259, IIb244-575, IIb566-841, IIIa22-262,
IIIa254-462, and IIIa708-762 were expressed in large quantities, but
the yields by affinity purification were low because of the formation
of insoluble aggregates. Therefore, these recombinant fragments and GST
were purified directly from bacterial lysates fractionated on
SDS-polyacrylamide gels. As shown in Figure
1, each purified preparation represented
major protein band consistent with the predicted molecular weight mass,
with or without additional bands. These extra protein bands were
completely absorbed by incubation with glutathione-Sepharose beads
and, therefore, were degradation products of recombinant GPIIb-IIIa
fragments. Densitometric analysis on silver-stained gels revealed that
more than 92% of the proteins in our preparations were recombinant
GPIIb-IIIa fragments.
T-cell proliferative responses to GPIIb-IIIa fragments The proliferative responses of peripheral blood T cells with the 6 recombinant GPIIb-IIIa fragments were examined, and representative results from 3 patients with ITP are shown in Figure 2. ITP2 responded to IIb18-259,
IIb566-841, and IIIa708-762; ITP18 responded to IIIa22-262; and
ITP21 responded to IIb18-259. Table 1 summarizes the T-cell
proliferative responses to recombinant GPIIb-IIIa fragments in 25 patients with ITP. Each patient showed a significant response to at
least one fragment, though 3 patients (ITP12, ITP18, and ITP22) were
negative for anti-GPIIb-IIIa antibodies at the time of examination. T
cells from the patients with ITP recognized the GPIIb-IIIa fragments in
various combinations, and 12 patients responded to 2 or more fragments.
Amino-terminal regions of both IIb and IIIa (IIb18-259 and
IIIa22-262) were frequently recognized (60% and 64%, respectively),
compared with the other fragments (IIb566-841, IIb244-575,
IIIa254-462, and IIIa708-762), which were recognized by 28%, 12%,
4%, and 12% of the patients, respectively. T-cell proliferative
responses to IIb18-259 or IIIa22-262 were detected in all but one
patient. These findings indicate that several distinct T-cell epitopes
are present on GPIIb-IIIa, but the immunodominant T-cell epitopes are
located within IIb18-259 and IIIa22-262.
All healthy donors who responded to trypsin-digested GPIIb-IIIa also
showed T-cell proliferative responses to 2 or more recombinant GPIIb-IIIa fragments in various combinations (Table
2). In contrast to findings in patients
with ITP, all 6 recombinant fragments were recognized in similar
frequencies. It was of note that T-cell responses to IIb
HLA and clinical associations with T-cell reactivities to GPIIb-IIIa fragments An association between the T-cell reactivities to individual GPIIb-IIIa fragments and the HLA-DRB1, -DQB1, and -DPB1 alleles was examined. No statistically significant associations were found in patients with ITP. However, when patients with ITP and healthy donors were combined, T-cell reactivity to IIb18-259 was detected in 9 of
10 of them with DRB1*0901 and in 9 of 25 without DRB1*0901 (P = .007).
Thirteen patients with ITP had T-cell responses to one fragment, and
the remaining 12 patients had responses to 2 or more fragments. When
demographic and laboratory findings were compared between these 2 patient groups, no differences were found in sex, age at the time of
diagnosis, platelet count at the time of blood examination, levels of
anti-GPIIb-IIIa antibodies in plasma and platelet eluates, or current
and previous treatment regimens (data not shown). However, the time
between diagnosis and blood examination for patients who responded to
one fragment was significantly longer than that for patients who
responded to 2 or more fragments (135.1 ± 91.7 vs 50.3 ± 60.2
months; P = .01). Figure 4
illustrates that a significant negative correlation between the number
of immunoreactive fragments and the time between diagnosis and blood
examination was detected (r = 0.52;
P = .008).
Serial analysis of T-cell reactivities to GPIIb-IIIa fragments in patients with ITP T-cell proliferative responses to GPIIb-IIIa fragments were serially examined in 14 patients with ITP. Immunoreactive fragments detected at the initial and later examinations were concordant in 11 patients. None of the patients developed T-cell responses to additional fragments during the follow-up, but 3 patients demonstrated a loss of fragment reactivity. ITP4 responded to 4 fragments IIb18-259, IIb566-841, IIIa22-262, and IIIa708-762at the first examination but responded to IIb18-259 and IIIa22-262 at follow-up examinations 10 and 18 months later. ITP2 lost T-cell reactivity to IIIa708-762, and
ITP7 lost reactivity to IIIa254-462 at the follow-up examinations. It
was noted that T-cell reactivities to immunodominant fragments were
consistently detected in all 14 patients examined. In contrast, T-cell
reactivities lost during follow-up were to nondominant fragments.
In vitro anti-GPIIb-IIIa antibody production in response to GPIIb-IIIa fragments Anti-GPIIb-IIIa antibody production was measured in PBMC cultures with recombinant GPIIb-IIIa fragments, and representative results are shown in Figure 5. PBMCs from ITP4 produced anti-GPIIb-IIIa antibodies in response to recombinant fragments IIb18-259, IIb566-841, and IIIa22-262. Samples from
this patient showed T-cell proliferative responses to these 3 fragments
in addition to IIIa708-762, which did not promote in vitro
anti-GPIIb-IIIa antibody production. In vitro anti-GPIIb-IIIa
antibody production was detected in ITP19 and ITP20 in response to
IIIa22-262 and IIb18-259, respectively. For these patients, the
fragments inducing T-cell proliferation were consistent with those
promoting in vitro anti-GPIIb-IIIa antibody production. Levels of
anti-GPIIb-IIIa antibodies in PBMC culture supernatants stimulated
with GST or individual GPIIb-IIIa fragments for 15 patients with ITP
and 7 healthy donors are summarized in Tables 1 and 2, respectively. In
patients with ITP, in vitro anti-GPIIb-IIIa antibody production was
induced by antigenic stimulation with at least one of the GPIIb-IIIa
fragments. In contrast, none of the PBMCs from healthy donors produced
anti-GPIIb-IIIa antibodies, though they showed T-cell proliferation to
2 or more GPIIb-IIIa fragments. To examine whether anti-GPIIb-IIIa
antibodies produced in in vitro cultures react with platelets, 10 randomly selected culture supernatants containing
anti-GPIIb-IIIa antibodies were incubated with platelets,
erythrocytes, or PBMCs obtained from healthy donors. Anti-GPIIb-IIIa
antibody reactivity was suppressed by incubation with platelets, but
not by incubation with erythrocytes or PBMCs (data not shown).
When the results of in vitro anti-GPIIb-IIIa antibody production were
compared with those of T-cell proliferation assays, it was found that
the immunodominant fragments IIb Characterization of GPIIb-IIIa-reactive T-cell lines Fifteen T-cell lines specific for platelet-derived GPIIb-IIIa were established from 5 patients with ITP. All these lines had a CD4+CD8 phenotype and responded to
trypsin-digested GPIIb-IIIa, but not to the mock-treated PBS control.
Antigen-induced proliferative responses in representative
GPIIb-IIIa-reactive T-cell lines are shown in Figure
6. Lines WY3 and FS4 responded to
IIIa22-262 and IIb18-259, respectively, in addition to
trypsin-digested GPIIb-IIIa. Eight T-cell lines reacted with one
GPIIb-IIIa fragment (2 with IIb18-259, 1 with IIb566-841, and 5 with IIIa22-262), and 6 lines reacted with 2 or 3 fragments (5 with
IIb18-259 and IIIa22-262, and 1 with IIb18-259, IIb566-841,
and IIIa22-262). One GPIIb-IIIa-reactive T-cell line did not respond
to any of the 6 fragments. In total, 13 of 15 T-cell lines that were
reactive with platelet-derived GPIIb-IIIa recognized IIb18-259,
IIIa22-262, or both, indicating again that T cells reactive with these
2 amino-terminal fragments are the predominant GPIIb-IIIa-reactive T
cells in the peripheral blood of patients with ITP.
HLA class II restriction, T-cell helper activity, and cytokine profiles
were further analyzed in the 8 GPIIb-IIIa-reactive T-cell lines that
responded to a single GPIIb-IIIa fragment (Table 3). HLA class II restriction was
determined according to the inhibitory effect of an anti-HLA class II
mAb on antigen-induced T-cell proliferation. As shown in Figure
7, IIIa22-262-induced proliferation was
inhibited by an anti-HLA-DR mAb in line WY3 and by both anti-HLA-DR
and anti-HLA-DP mAb in line WY9. All GPIIb-IIIa-reactive T-cell lines
were restricted by HLA-DR, but line WY9 was restricted by both HLA-DR
and HLA-DP.
Representative results of the helper activity promoting
anti-GPIIb-IIIa antibody production in GPIIb-IIIa-reactive T-cell lines are shown in Figure 8A. The
IIb
In this study, we examined T-cell responses to a series of
recombinant GPIIb-IIIa fragments in 25 patients with ITP. Our results indicate that the immunodominant epitopes recognized by
GPIIb-IIIa-reactive T cells in patients with ITP are located within
the amino-terminal regions of both GPIIb The current study further confirmed the presence of autoreactive T
cells to GPIIb-IIIa in healthy donors without having detectable anti-GPIIb-IIIa antibodies.10,22 The kinetics of T-cell
responses to immunodominant GPIIb-IIIa fragments in patients with ITP
were accelerated compared with that of healthy donors, as observed in a
T-cell response to trypsin-digested GPIIb-IIIa.10
Anti-GPIIb-IIIa antibody synthesis was observed in PBMC cultures of
patients with ITP, but not in cultures of healthy donors, in response
to recombinant GPIIb-IIIa fragments. This is analogous to autoantibody
responses to topoisomerase I in scleroderma23 and to
B-cell epitopes on GPIIb-IIIa recognized by autoantibodies from
patients with ITP have been extensively analyzed by examining competitive binding between human antibodies and murine mAbs as well as
B-cell reactivities to enzyme-cleaved GPIIb-IIIa fragments or synthetic
peptides.25-32 Previously reported antigenic epitopes include a 33-kd chymotryptic core fragment of GPIIIa, encoding cysteine-rich domains,25 a carboxyl-terminal cytoplasmic
portion of GPIIIa,26 a 65-kd chymotryptic
carboxyl-terminal fragment of IIb Here, we found that anti-GPIIb-IIIa antibody production was induced in
vitro by antigenic stimulation with IIb Findings from the current study and our previous report10
suggest that the epitopes recognized by GPIIb-IIIa-reactive T cells
are cryptic but the factors that induce the expression of cryptic
determinants and activate GPIIb-IIIa-reactive CD4+ T cells
in patients with ITP are unknown. Lehmann et al34 proposed that, in autoimmunity, de novo presentation of a previously cryptic self-determinant is induced by up-regulated antigen presentation capacity and shifts in peptide hierarchy. In this process,
antigen-presenting cells in a local milieu play a central role through
an activated antigen-processing pathway and increased expression of
adhesion and costimulatory molecules. In addition, shifts in peptide
hierarchy resulting in the expression of cryptic self-peptides are
shown to be induced by events that affect the normal processing of
self-proteins, such as an unusual cleavage or a complex formation with
other proteins.35-37 These modifications are presumed to
subsequently mask or unmask cleavage sites for proteinases and
reductases in endosomes, resulting in the expression of previously
cryptic self-peptides. In this regard, it is plausible that the changes
of structural conformation of GPIIb It is interesting to note that the number of immunoreactive GPIIb-IIIa
fragments was negatively correlated with the time between diagnosis and
blood examination. Serial analysis of GPIIb-IIIa fragment-induced
T-cell proliferation revealed that 3 of 14 patients lost T-cell
reactivity to the previously recognized fragments during follow-up.
These findings suggest that patients with ITP have T cells that are
responsive to a variety of epitopes on GPIIb-IIIa early in the course
of the disease and that their T-cell repertoires to the immunodominant
epitopes are selectively expanded, whereas those to nonimmunodominant
epitopes fade during the course of the disease. It has been shown in
animal models that an autoimmune response is initiated to one epitope
and subsequently spreads to other sites on the same molecules, a
concept called epitope spreading.39,40 However, epitope
spreading is rarely observed in patients, probably because it has
already occurred before the clinical onset of the disease. On the other
hand, a reduction in isotype expression and epitope reactivity of
autoantibody responses during follow-up was observed in patients with
mixed connective tissue disease41 and
scleroderma,42 independent of treatment. It was also noted
that peripheral blood T cells from healthy donors reacted with 2 or
more GPIIb-IIIa fragments, but IIb In summary, our results indicate that GPIIb-IIIa-reactive
CD4+ T cells in patients with ITP recognize several
distinct epitopes on GPIIb-IIIa, but the amino-terminal extracellular
domains of both GPIIb
We thank Yuka Okazaki and Kyoko Kimura for their expert technical assistance and Dr Kenichi Furihata for helpful suggestions.
Submitted December 4, 2000; accepted March 7, 2001.
Supported by the Keio University Medical Science Fund (M.K.), by a grant from the Japanese Ministry of Health and Welfare (Y.I.), and by grants from the Ministry of Education, Science, Sports and Culture of Japan (S.K. and Y.I.).
The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734.
Reprints: Masataka Kuwana, Institute for Advanced Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan; e-mail: kuwanam{at}sc.itc.keio.ac.jp.
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  X.-L. Zhang, J. Peng, J.-Z. Sun, J.-J. Liu, C.-S. Guo, Z.-G. Wang, Y. Yu, Y. Shi, P. Qin, S.-G. Li, et al. De novo induction of platelet-specific CD4+CD25+ regulatory T cells from CD4+CD25- cells in patients with idiopathic thrombocytopenic purpura Blood, March 12, 2009; 113(11): 2568 - 2577. [Abstract] [Full Text] [PDF]
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 S. Nomura, K. Ishii, N. Inami, T. Matsuzaki, M. Yamaoka, F. Urase, Y. Maeda, and S. Fukuhara Antiglycoprotein IIb-IIIa Autoantibody in a Patient With Immune Thrombocytopenia After Cord Blood Transplantation Clinical and Applied Thrombosis/Hemostasis, February 1, 2009; 15(1): 123 - 124. [PDF]
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J. Yu, S. Heck, V. Patel, J. Levan, Y. Yu, J. B. Bussel, and K. Yazdanbakhsh Defective circulating CD25 regulatory T cells in patients with chronic immune thrombocytopenic purpura Blood, August 15, 2008; 112(4): 1325 - 1328. [Abstract] [Full Text] [PDF]
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H. Sukati, H. G. Watson, S. J. Urbaniak, and R. N. Barker Mapping helper T-cell epitopes on platelet membrane glycoprotein IIIa in chronic autoimmune thrombocytopenic purpura Blood, May 15, 2007; 109(10): 4528 - 4538. [Abstract] [Full Text] [PDF]
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M. Sakakura, H. Wada, Y. Abe, J. Nishioka, H. Tomatsu, Y. Hamaguchi, S. Oguni, H. Shiku, and T. Nobori Usefulness of Measurement of Reticulated Platelets for Diagnosis of Idiopathic Thrombocytopenic Purpura Clinical and Applied Thrombosis/Hemostasis, July 1, 2005; 11(3): 253 - 261. [Abstract] [PDF]
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F. P. Panitsas, M. Theodoropoulou, A. Kouraklis, M. Karakantza, G. L. Theodorou, N. C. Zoumbos, A. Maniatis, and A. Mouzaki Adult chronic idiopathic thrombocytopenic purpura (ITP) is the manifestation of a type-1 polarized immune response Blood, April 1, 2004; 103(7): 2645 - 2647. [Abstract] [Full Text] [PDF]
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M. Kuwana, S. Nomura, K. Fujimura, T. Nagasawa, Y. Muto, Y. Kurata, S. Tanaka, and Y. Ikeda Effect of a single injection of humanized anti-CD154 monoclonal antibody on the platelet-specific autoimmune response in patients with immune thrombocytopenic purpura Blood, February 15, 2004; 103(4): 1229 - 1236. [Abstract] [Full Text] [PDF]
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M. Kuwana, Y. Kawakami, and Y. Ikeda Suppression of autoreactive T-cell response to glycoprotein IIb/IIIa by blockade of CD40/CD154 interaction: implications for treatment of immune thrombocytopenic purpura Blood, January 15, 2003; 101(2): 621 - 623. [Abstract] [Full Text] [PDF]
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 M. Kuwana, Y. Okazaki, J. Kaburaki, Y. Kawakami, and Y. Ikeda Spleen Is a Primary Site for Activation of Platelet-Reactive T and B Cells in Patients with Immune Thrombocytopenic Purpura J. Immunol., April 1, 2002; 168(7): 3675 - 3682. [Abstract] [Full Text] [PDF]
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 D. B. Cines and V. S. Blanchette Immune Thrombocytopenic Purpura N. Engl. J. Med., March 28, 2002; 346(13): 995 - 1008. [Full Text] [PDF]
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Top
Abstract
Introduction
3 integrin or CD41/CD61, which is a
calcium-dependent heterodimeric membrane receptor for fibrinogen and
other ligands.
