Immunosuppression of experimental allergic encephalomyelitis in guinea pigs by antibrain and antithymocyte heteroantisera.

Experimental allergic encephalomyelitis (EAE), induced by central nervous system (CNS) myelin basic protein (MBP) in adjuvant, is considered a thymus dependent autoimmune disease. Brain contains the thymic antigen, thy 1. The possibility that brain associated anti thy 1 immunoglobulin may be provoked in certain pathologic conditions of the CNS suggested a comparative evaluation of brain and thymocyte antisera on the development of EAE. Antisera produced in rabbits against brain from guinea pigs, rats and mice or fetal guinea pig thymus were highly reactive against thy 1 containing cells when assessed by indirect immunofluorescent staining or complement-mediated cell lysis. Treatment of guinea pigs with heteroantisera to guinea pig and mouse, but not to rat brain, for 3 days around the time of MBP sensitization markedly reduced physical signs of disease, particularly paralysis, but had little effect on the development of inflammatory lesions in the CNS. Anti-guinea pig thymocyte sera eliminated all physical signs of EAE with only residual pathology. These results establish the relative immunosuppressive effect of brain and thymocyte antisera in EAE and corroborate the thymus-dependent nature of EAE in guinea pigs.