ABSTRACT
AIM: To identify T cell expansions, i.e. increased frequencies of T cells using a particular T cell receptor (TCR) V alpha or V beta gene segment, in patients with immune thrombocytopenic purpura (ITP). METHODS: The TCR repertoires of CD4+ and CD8+ peripheral blood lymphocytes of 16 patients with chronic ITP were analysed by staining with a panel of anti-TCR V alpha and V beta antibodies followed by flow cytometry. RESULTS: Four of the 16 patients exhibited a total of 6 expansions of CD8+ T cells using a particular V beta segment, but no expansions were detected in the CD4+ subset. For three of the expansions where a follow-up blood sample after treatment with intravenous immunoglobulin was available, only one expansion remained. CONCLUSION: Overall T cell expansion frequency was the same as in healthy individuals. However, the presence of expansions that normalized with treatment suggests the presence of specific T cells implicated in the pathogenesis of ITP.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Genes, T-Cell Receptor beta/immunology , Purpura, Thrombocytopenic, Idiopathic/immunology , Adolescent , Child , Child, Preschool , Female , Flow Cytometry , Fluorescent Antibody Technique , Humans , MaleABSTRACT
During the past few decades a number of studies has described T cell defects and attempted to elucidate their role in the pathogenesis of idiopathic thrombocytopenic purpura (ITP). Some studies implicate T cells as potential initiators of autoantibody production in ITP. However, only a few of these have studied the role that the T cell receptor may play in the pathogenesis of ITP. In a variety of autoimmune syndromes interest has focused on the alpha- and beta-chains of the T cell receptor. Deviations from the normal T cell receptor gene usage have been reported in rheumatoid arthritis, systemic lupus erythaematosus and multiple sclerosis. Usually, these studies have shown a restricted heterogeneity of T cell receptor variable gene usage. The studies on the T cell receptor in ITP have included a limited number of patients, which makes it difficult to evaluate the significance of the role that the T cell receptor may play in the pathogenesis of ITP. Further studies are warranted.