[Induction of immune tolerance to thymus-dependent antigen (sheep erythrocytes) in the absence of T-cells].

The role of T cells in B cell tolerance induction to sheep red blood cells (SRBC) was studied in intact adult mice, in lethally irradiated mice injected with singeneic embryonic liver cells and thymocytes (TB-mice) and in animals functionally deprived of T cells--thymectomized, letally irradiated mice reconstituted with embryonic liver cells only (B-mice). Tolerance was obtained by treatment of mice with SRBC and cyclophosphamide (Cy). Cy-induced tolerance to SRBC was shown to be the result of the absence of specific T cells and partially of immunocompetent B cells. Suppression of immunoreactivity was observed not only in TB-mice but also in B-mice subjected to tolerogenic treatment. Splenocytes of tolerant TB-mice did not suppress the immune response of intact spleen cells to SRBC. The results obtained suggest the conclusion that B cells tolerance could be formed in absence of T cells.