Antigen-induced inhibition of experimental allergic encephalomyelitis. II. Studies in guinea pigs with the small rat myelin basic protein.

The smaller of the two rat myelin basic proteins (rat-S) was isolated by gel filtration and employed for antigen-induced inhibition of experimental allergic encephalomyelitis (EAE) in guinea pigs. Rat-S lacks a sequence of 40 amino acids which are present in the larger myelin basic protein including part of the major determinant which causes EAE in the guinea pig. The results show that non-encephalitogenic rat-S, given before sensitization with the large basic protein, significantly inhibits EAE in the guinea pig, although the protection provided by the large basic protein is somewhat more complete. These findings suggest that different sites on the basic protein molecule are responsible for the immunologic induction and inhibition, respectively, of EAE.