Regulation of experimental allergic encephalomyelitis. III. Demonstration of effector cells in tolerant rats.

Effector cells, which transfer experimental allergic encephalomyelitis (EAE), can be demonstrated in the spleens of Lewis rats which have been rendered tolerant to myelin basic protein (BP). Transfer of EAE was achieved following in vitro culture of tolerant donor spleen cells with antigen. The donor animals were, themselves, protected against EAE induced by active challenge with BP in complete Freund's adjuvant, although BP-activated effector spleen cells could partially override this protection. The finding that effector cells are present in unresponsive animals supports the hypothesis that immunologic self tolerance is actively regulated by suppressor mechanisms.