Antigen-induced strain-specific autoantiidiotypic antibodies modulate the immune response to dextran B 512

Sera from CBA and C57BL mice immunized against dextran B 512 eight or more days earlier contain mainly IgG antibodies that specifically suppress the development of plaque-forming cells against dextran in vitro. Suppression was not caused by antibodies against the alpha 1-6 epitope of dextran to any major extent. Sera from CBA mice (IgCH allotype j) suppressed plaque-forming cells from CBA mice, whereas sera from C57BL mice (allotype b) inhibited plaques from C57BL and CBA/Ig-1b mice. Sera from dextran-tolerant mice or from mice that are genetic unresponders to dextran did not suppress plaque-forming cells. Both thymus-independent and thymus-dependent forms of dextran induced the appearance of these autoantiidiotypic antibodies that can distinguish between anti-alpha 1-6 antibodies produced in mouse strains having different IgCH-locus-determined allotypes.