Biological Activity of an Encephalitogenic Fragment in the Monkey

A 45-residue encephalitogenic fragment of myelin basic protein has been prepared by extraction of acetone-ether defatted Rhesus monkey brain at pH 3.5 followed by Sephadex G-50 and carboxymethylcellulose chromatography. A ninhydrin-stained tryptic peptide map showed it to be free of contamination. A dose of 1.5 mg per animal produced the classical clinical and histological changes of experimental allergic encephalomyelitis 3 to 4 weeks after challenge in three out of three Rhesus monkeys. This fragment contains the region around tyrosine 69 which is encephalitogenic in the rabbit but does not contain the other active region of the molecule.