Suppression of Synthesis of Allotypically Defined Immunoglobulins and Compensation by another Sub-class of Immunoglobulin

Abstract

AMONG the light chains of the rabbit immunoglobulin molecules four allotypically determined molecular species can be distinguished : A4, A5, A6¹ and A9². These specificities are determined by allelic genes at the A_b allotypic locus^1,2. Thus a rabbit homozygous at this locus synthesizes only one of these specificities, but a heterozygous rabbit synthesizes two. The phenotypic expression of the synthesizing capacity of heterozygotes can be altered by administration of anti-allotype antibody; synthesis of immunoglobulins of the paternal type can be inhibited (“suppressed”) either by uterine transfer^3–7 of allotype antibody from the mothers immunized against the allotypic specificity of the prospective father⁸ or by injecting the young rabbits with allotype antiserum during the first few days of life^9–11. When a heterozygous rabbit is exposed to anti-allotype serum the resulting suppression of one allotypic specificity is compensated by increased synthesis of the product of the second allele; thus the total concentration of IgG is not affected and is similar to that of the normal rabbits^9,11.