Experimental Allergic Encephalomyelitis (E.A.E.): Synthesis of the 7–11, 11–20, and 12–20 Peptides of Human Encephalitogenic Protein and Inhibition of Histological E.A.E. by the 12–20 Peptide

Peptides comprising the 7–11, 11–20, and 12–20 sequences of human encephalitogenic basic protein (HEP) were synthesized by the solid-phase procedure, purified by gel-filtration and high-voltage paper electrophoresis, and characterized by amino acid analysis, thin-layer chromatography, high-voltage paper electrophoresis, and paper chromatography.The peptides were studied for the capacity to induce E.A.E. when injected with Freund's complete adjuvant (FCA) into guinea pigs. The same peptides were also studied for the capacity to inhibit development of E.A.E. in guinea pigs injected with peptide/FCA 28 days before injection with encephalitogenic HEP in FCA. The results were as follows: (1) all three peptides induced mild clinical E.A.E. but the 12–20 peptide induced severe disease in five out of 40 guinea pigs; (2) none induced histological lesions typical of E.A.E.; (3) none induced antibody reactive with 125I-HEP; (4) none induced delayed sensitivity to the homologous peptide or HEP; (5) injection of the 12–20 peptide in FCA inhibited the development of histological E.A.E. in guinea pigs injected later with HEP/FCA, whereas the 7–11 and 11–20 sequences did not; (6) humoral immunity to injection of HEP/FCA was not prevented by prior injection of the synthetic peptides in FCA.