Abstract
Discrete populations of anti-S49 antibodies were found in the antisera of Lewis rats recovered from S49-induced experimental allergic encephalomyelitis (EAE). A potent inducer of EAE in Lewis rats, S49 is a synthetic peptide representing residues 69–84 of bovine myelin basic protein but with deletions at Gly-77 and His-78 to form an analogue of guinea pig or rat 69–84, GSLPQKAQRPQDENG. Each population within a given antiserum, as identified by Scatchard and Sipsian window analysis, was found to exhibit reactivity for a different S49 determinant, and the affinities of each population were relatively restricted and discontinuous. The high affinity populations (107–108 M−1) were cross-reactive with YS8 (YGSLPQKAQGHRPQDENG) in equilibrium competitive inhibition reactions whereas the low affinity populations (105–106 M−1) were reactive only with S49 and YS49 among a panel of peptide analogues. Of the YS8 cross-reactive antibodies the highest affinity (108 M−1) were also cross reactive with S81 (YGSLPQKAQGHRPQDEG) but not S49 (69-84-Gly), thus emphasizing the need for Tyr-68 for format stability of the determinant involved. The other YS8 cross-reactive population (107 M−1) was completely reactive with S49 but totally unreactive with S81 in equilibrium reactions, thus emphasizing the requirement for Asn-84 but not Tyr-68 for the determinant's topographic stability. Peptides shorter than S49 from the N-terminal end, but retaining the sequences AQRPQDEN or SQRSQDEN (suspected residence of minimal encephalitogenic determinants), reacted only under conditions of two-step non-equilibrium competitive inhibition assays. Such reactions would occur only at very low affinity (<105 M−1) with the anti-S49 antibodies. It was hypothesized that the encephalitogenic T-cell determinant for Lewis rats, although permitting B-cell responses at very low affinity, may exclude high affinity responses in susceptible animals.
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This work supported at Duke University Medical Center by research grant NS-10237 from the National Institutes of Health of the U.S. Public Health Service, Immunology Training Grant #5-T32-CA-09058-10, and Medical Scientist Training Program #5-T32-OM-07171-08, and at St. Luke's Hospital Center by NS-21466 from the National Institutes of Health and RG1197-B7 from the National Multiple Sclerosis Society.
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Day, E.D., Hashim, G.A., Potter, N.T. et al. Immunochemical analysis of Lewis rat antisera to the synthetic encephalitogenic peptide S49. Neurochem Res 10, 1587–1603 (1985). https://doi.org/10.1007/BF00988601
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DOI: https://doi.org/10.1007/BF00988601