RESUMO
Objective To investigate the role of activated T lymphocytes in the pathogenesis and effect of CD95 and bcl 2 expression on the development of alopecia areata. Methods The lymphocytes were isolated from the peripheral blood of the patients. Then CD4 +, CD8 +,and/or CD95 and bcl 2 positive lymphocytes were sorted out by flow cytometry . Results In the active stage of the disease, CD4 + lymphocytes decreased while CD8 + lymphocytes increased significantly. At the same time, the expression of bcl 2 was much more frequently detected in CD8 + lymphocytes than in CD4 +lymphocytes. CD95 expression was also increased markedly in T lymphocytes. Conclusions Down regulation of bcl 2 leads to the decrease in number of CD4 + lymphocytes. Meanwhile, CD8 + lymphocytes increased duo to the over expression of bcl 2. As a result , the ratio of CD4 + to CD8 +lymphocytes has dropped markedly and the cytotoxic effect of CD8 +lymphocytes on the hair follicles is enhanced. On the other hand, over expression of CD95 in T lymphocytes triggers cell apoptosis in the hair follicles. Both effects promote the development of alopecia areata . [