The immune response to heterologous red cells in mice. IV. Induction of unresponsiveness to weakly immunogenic red cells by cyclophosphamide and cortisone acetate.

Recovery from cyclophosphamide-induced unresponsiveness to multi-species erythrocytes in adult mice was found to depend on immunogenicity of the red cells tested. Under conditions which did not allow development of tolerance to sheep red cells (SRBC), specific unresponsiveness to red cells from hamster (HRBC) or gerbil (GRBC) was achieved, even using comparatively low antigen doses. Following administration of cortisone acetate only partial tolerance to the weakest immunogen (GRBC) could be demonstrated. Results are interpreted in terms of possible mechanisms of drug action.