Abstract
In a previous publication (Imnunol. Comm. 3:219, 1974) a hypothesis was proposed that the high dose inhibition of enceph-alitogenicity in guinea pigs seen with the tryptophan peptide, phe ser trp gly ala glu gly gln arg, and not observed with the whole myelin basic protein which contains this sequence, was the result of competitive inhibition by non-encephalitogenic fragments of the tryptophan peptide produced in vivo possibly by exopeptidases. I present data which disagrees with this hypothesis.