Sex difference in the CD4 + CD45R + T lymphocytes in normal individuals and its selective decrease in women with idiopathic thrombocytopenic purpura

Chronic idiopathic thrombocytopenic purpura (ITP) is a well-defined autoimmune hematologic disorder. It is more common in women than men. We have shown that patients with active disease have abnormal T cell subsets which are more perturbed in women than in men and functional abnormalities that are confined to the T lymphocytes. In the current study, the anti-2H4 (CD45R) monoclonal antibody was used to divide the CD4 subset into their CD4+CD45R+ and CD4+CD45R− T lymphocytes. The sub-populations were measured in the peripheral blood of 26 women and 15 men with active ITP, 16 women and 8 men with disease in remission, and 33 normal healthy women and men. Normal women had increased percentages ( P < 0.0001) and numbers ( P < 0.005) of the CD4+CD45R+ lymphocytes compared to normal men. Women with active disease had reduced percentages and numbers of CD4+CD45R+ lymphocytes compared to normal women ( P < 0.0001) and women with disease in remission ( P < 0.001). Those women with decreased CD4+CD45R+ lymphocytes had a significantly depressed lymphocyte response to polyclonal T cell mitogens. In contrast, men with active disease had neither such phenotypic changes nor functional correlations. The percentages and numbers of CD4+CD45R− lymphocytes were not changed in either sex with active disease. In conclusion, women, but not men, with active ITP appear to possess a reduced sub-population of CD4+CD45R+ T lymphocytes.