Allotype Suppression with Anti-b5 Antiserum in b5b5 Homozygous Rabbits Fostered in Uteri of b4b4 Homozygous Mothers: Compensation by Allotypes at Other Loci

Abstract

Abstract Sera of b5c7 and b5c7c21 rabbits injected at birth with anti-b5 antiserum after being fostered in uteri of b4b4 homozygous mothers were analyzed for b4γG, b5γG, c7γG, c21γG and total γG immunoglobulin concentrations by radial diffusion analysis and by precipitation of 125I-labeled γG immunoglobulins with anti-allotype antisera. A single injection of 4.5 mg of anti-b5 antibody resulted in a marked suppression of the appearance of the b5 allotype in b5b5 homozygotes for periods up to 14 weeks. The b5c7c21 offspring suppressed with a single injection of anti-b5 had no detectable b5 allotype until 12 weeks of age, but instead had relatively high compensatory levels of the c7 and c21 allotypes. Thereafter the relative level of b5γG increased until by 60 weeks of age the b5γG constituted over 90% of the total γG. Essentially 100% of the 125IγG immunoglobulins of the b5c7c21 rabbits could be precipitated with anti-b5, anti-c7 and anti-c21. The b5 suppressed b5c7 offspring had no detectable b5γG until 12 weeks of age, and increased levels of c7γG again were evident. Up to 60% of the 125IγG immunoglobulins could be shown to lack both the b5 and c7 allotypes in the b5c7 rabbits. A subsequent injection of 4.5 mg of anti-b5 antibody given at 12 weeks of age resulted in a marked suppression of the appearance of the b5 allotype. No b5γG has been detected in the sera of these rabbits for at least 7 months.