Antigenic regions for the humoral response to myelin basic protein

Abstract

The major encephalitogenic sites in myelin basic protein (BP) † † BP, myelin basic or encephalitogenic protein; CFA, complete Freund's adjuvant; CM-cellulose, carboxymethyl-cellulose; DEAE-cellulose, diethyla-minoethylcellulose; DA-RIA, double antibody-radioimmunoassay; EAE, experimental allergic encephalomyelitis; HSA, human serum albumin; MBSA, methylated bovine serum albumin; RSA, rabbit serum albumin. differ among animals tested. In order to define further the antigenic features of BP and to explore the possibility that antigenic sites recognized for antibody production might also differ among species, the contribution of regions of BP to the total antigenic activity of the molecule was examined in guinea pigs and rabbits. Twenty-one guinea pigs, 13 Hartley and 8 strain 13, were given a series of immunizations with bovine or guinea pig BP administered with large amounts of Mycobacterium tuberculosis. Eleven New Zealand white rabbits were immunized with bovine or guniea pig BP alone or conjugated to albumin. Antisera were tested by double antibody radioimmunoassay for reactivity with BP and BP peptides. Antisera from all guinea pigs reacted with BP and peptide 89–169 but had little or no reactivity with peptides 1–36 and 43–88. All rabbit antisera reacted well with BP, peptide 89–169 and peptide 1–36. Reactivity of rabbit antisera with peptide 43–88 was variable. It was present, usually in low titers, in 5 animals. The pattern of reactivity of rabbit antisera to BP and BP peptides was established early during the course of immunization. Rabbit antisera reactive with BP peptide 43–88 showed limited, if any, activity toward peptide 79–88, thus providing additional information about the inaccessibility or conformational dependence of the antigenic site in the molecular region of residues 79–88.