The immune response of Lewis rats to peptide 68-88 of guinea pig myelin basic protein. II. B cell determinants.

A series of peptides, produced from peptide 68-88 by selective enzyme cleavage, were used to define the amino acid sequences reactive with Lewis rat anti-peptide 68-88 antibody. One hundred per cent of 38 rats immunized with peptide 68-88 recognized a B cell determinant residing in the region of residues 80-88. The three carboxy-terminal amino acids, residues 86-88, appeared to confer conformation on this determinant. In roughly two-thirds of the rats, the reactivity with this major B cell determinant was equal to the reactivity with the immunizing peptide. In these rats the anti-peptide 68-88 antibodies were of the IgG2 class. A third of the rats recognized an additional determinant(s) and in these the predominant class of antibody was IgG1.