An Effect upon the Regulation of Gene Expression: Allotype Suppression at the a Locus in Heterozygous Offspring of Immunized Rabbits

Abstract

Sera of a¹a³b⁴b⁵ heterozygous rabbits exposed to maternal anti-al or anti-a3 were analyzed for a1, a3, b4, b5 and total γG-immunoglobulin concentrations by a radial diffusion method in serum agar gel plates. The a¹a³ offspring of an a¹a¹ mother making anti-a3 developed relatively low levels of the paternal a3 allotype whereas the heterozygous offspring of an a³a³ mother making anti-a1 developed relatively low serum levels of the paternal a1 protein. In these litters the phenotypic expression of the b5 allele introduced by the paternal genome was unaffected. The altered phenotypic expression of immunoglobulin allotypes controlled by the a locus persists for at least 23 months. The phenomenon of “allotype-suppression,” originally found as an isoantibody effect upon expression of alleles of the b locus, controlling determinants on the light polypeptide chains of immunoglobulins is now shown also to occur with the alleles of the unlinked a locus which controls antigenic determinants associated with the heavy chains of the immunoglobulins. It is possible that this phenomenon is a reflection of the feedback control of immunoglobulin production.