Differential effect of cyclosporine in vivo on the distribution of T cell subsets in the thymus, spleen, and lymph nodes.

Abstract

Cyclosporine treatment of BALB/c mice (at a dose of 20 mg/kg every other day for 3 weeks) caused a remarkable reduction in the PNA-, L3T4+Lyt-2- subset of thymocytes. A significant reduction of the L3T4+Lyt-2-subset was also observed in both the lymph node and spleen cells of CsA-treated mice, though the degree of the reduction was lower than that in thymocytes. Both lymph node and spleen cells from CsA-treated mice showed a significant increase in the percentage of Thy-1.2 negative, L3T4-Lyt-2- cells (perhaps B cells). Thymocytes from CsA-treated mice showed a reduction in the in vitro proliferative responses to Con A and PHA. On the other hand, there was a slight, but not significant, decrease in the responses of lymph node cells to Con A, PHA and LPS. Spleen cells from CsA-treated mice showed a significant reduction in the responses to Con A and PHA, though the degree of the reduction was lower than that of thymocytes. There was a significant decrease in the proliferative response of spleen cells to LPS. These results suggest that CsA affects both thymus and spleen cells in vivo, preferentially impairing the L3T4+Lyt-2- subset (helper T cells or their precursors) within the thymus. The lymph node cells seem to be relatively spared from the in vivo effect of CsA compared with cells in the thymus and spleen.