Athymic (nude) mice fail to delete functional self-reactive helper T cells.

We have examined the thymic requirement for the antibody response to a foreign antigen coupled to self erythrocytes. We find that self erythrocytes mediate thymus-independent, carrier specific help for the antibody response to the pneumococcal cell wall polysaccharide antigen, PnC. Thus, athymic nude mice gave a high primary antibody plaque-forming cell (PFC) response to PnC-mouse RBC but a low response to PnC coupled to sheep or burro RBC. The meager response to PnC coupled to foreign RBCs could not be attributed to antigenic competition since the response to the carrier (burro RBC) was < 100 PFC per spleen. Reconstitution of nude mice with splenic T cells from euthymic mice enhanced rather than suppressed the antibody response to PnC-mouse RBC. The results document that in the absence of thymic deletion, functional self-reactive helper cells persist in the nude mouse.