American blood donors seropositive for human T-lymphotropic virus types I/II exhibit normal lymphocyte subsets

Recent reports have demonstrated that some lymphocyte subsets are abnormal in Japanese blood donors who are seropositive for human T-lymphotropic virus type I (HTLV-I). To determine if similar changes characterize American blood donors who are seropositive for HTLV-I/II, lymphocyte subsets were measured in 42 HTLV-seropositive and 42 HTLV-seronegative blood donors. The seronegative individuals were matched by age, race, and gender to the seropositive individuals. Peripheral blood mononuclear cells were treated with a panel of 12 monoclonal antibody pairs and then analyzed by two-color flow cytometry. No significant differences were observed between the seropositive and seronegative groups with respect to the absolute number of circulating lymphocytes or the percentages of lymphocytes belonging to the subsets assessed. These subsets included B, T, CD4, and CD8 cells and subpopulations of CD4 and CD8 cells defined by the coexpression of markers that appear (CD25, HLA-DR, CD38) or disappear (Leu 8, CD45RA) after activation. These findings indicate that HTLV-seropositive persons in the American blood donor pool do not exhibit the lymphocyte subset alterations reported for HTLV-I-seropositive blood donors in Japan.