Heavy chain variable region allotypic subspecificities of rabbit immunoglobulins. II. Selective escape of the a1-AB Ig subpopulation after the induction of auto anti-a1 antibody.

An a1a2 rabbit (P286-3), neonatally suppressed for the expression of the a1 allotype, was immunized with autologous a1 IgG at 2 months of age. Both auto anti-a1 Ab and a1 IgG molecules were found in the serum of this rabbit after the auto-immunization. The auto anti-a1 Ab and the IgG from the auto anti-a1 Ab-depleted serum were isolated. Of the previously defined a1-AB, a1-AC, and a1-AD Ig subpopulations, the a1 IgG in the IgG preparation from the rabbit P286-3 were all of the a1-AB Ig subpopulation. The auto anti-a1 Ab from rabbit P286-3 did not react with the a1-A, a1-B, and a1-C allotypic subspecificities; thus, it was presumably specific for the a1-AC and a1-D allotypic subspecificity. Thus, the a1-AB Ig subpopulation escaped from allotype suppression in rabbit P286-3, whereas the a1-AD Ig subpopulation remained suppressed. The a1-AD Ig subpopulation will probably remain suppressed for a long time and perhaps permanently since rabbit P286-3 has produced circulating auto-Ab specific for the a1-D allotypic subspecificity. These results indicate that the a1 Ig subpopulations are synthesized by distinct clones of lymphocytes under separate control.