Protection against experimental allergic encephalomyelitis with complete Freund's adjuvant is unaffected by ionizing irradiation.

Long-lasting resistance to experimental allergic encephalomyelitis (EAE) was obtained in Lewis rats either by an immunization with complete Freund's adjuvant blended with aluminum hydroxide (ALU-CFA) or by convalescence from EAE. Total body irradiation at a dose of 500 R given both 1 day after ALU-CFA (or disease induction) and EAE challenge did not abrogate the protection. No antibodies against myelin basic protein could be detected in irradiated animals. In contrast high antibody titers were measured in non-irradiated controls recovered from EAE and subsequently resistant to the disease. Therefore it is unlikely that antibodies against myelin basic proteins are of any importance in protection from EAE. The studies suggest that unspecific radioresistant suppressor cells play a role in resistance to EAE.