Effects of cyclosporin A and insulin on peripheral lymphocytes in BB/W rats

The effects of cyclosporin A (Cs-A) and insulin on peripheral lymphocytes in BB/W rats were studied. The cumulative incidence of overt diabetes in untreated BB/W rats was 72% up to 120 days of observation, whereas the incidence was 13% in Cs-A-treated rats. Lymphocytopenia, consisting of decreased OX19+ (pan T), W3/25+ (helper/inducer T) and OX8+ (cytotoxic/suppressor T) cells, was present in BB/W rats. Cs-A significantly decreased both the percentage and the absolute number of OX8+, OX6+ (Ia-positive) and OX12+ (B) cells, and augmented the ratio of W3/25+ to OX8+ cells in BB/W rats. On the other hand, insulin injection significantly decreased the percentage of OX6+ cells and the ratio of W3/25+ to OX8+ cells in BB/W rats. Thus, rearrangement of the ratio of helper/inducer T to cytotoxic/suppressor T cells and reduction in the number of Ia antigen-bearing cells could be important for the inhibitory effects of diabetes in BB/W rats upon treatment with Cs-A or insulin.