Persistent Altered Phenotypic Expression of Allelic γG-Immunoglobulin Allotypes in Heterozygous Rabbits Exposed to Isoantibodies in Fetal and Neonatal Life

Abstract

Summary Sera of b4 b5 heterozygous offspring exposed to anti-b5 or anti-b4 in fetal or neonatal life were analyzed for b4, b5 and total γG-immunoglobulin concentrations by a micro-quantitative precipitin method and by the quantitative gel diffusion method of Oudin. Sera of unexposed rabbits were similarly analyzed. Rabbits of genotype b4 b5 which received maternal anti-b5 during fetal life from b4 b4 mothers immunized with b5, had a substantially lower per cent of total γG-immunoglobulin with the b5 allotype throughout life (up to 3 years) compared with control animals from nonimmunized mothers. In the affected animals, the total γG levels appeared normal and a compensatory increased production of the alternative allelic allotype accounted for most of the γG-immunoglobulin in their sera. The same phenomenon occurred when b4 b5 offspring of nonimmunized b4 b4 mothers were injected soon after birth with anti-b5 antiserum; 1 ml of serum containing 0.9 mg of precipitable antibody protein was sufficient to induce the phenomenon. In the reverse situation, when the b4 b5 offspring of a b5 b5 mother was injected after birth with anti-b4, a persistent reduction in the b4 level of the treated animal resulted compared with the control littermates. A compensatory increased production of b5 γG was observed.