Localization by Immunofluorescence of Gamma-Globulin Allotypes in Lymph Node Cells of Homozygous and Heterozygous Rabbits.

The cellular production of two rabbit γ-globulin allotypic specificities, A4 and A5, determined by allelic genes was investigated by the fluorescent antibody method. The 7S γ-globulin fractions of precipitating antisera were conjugated to fluorescein isothiocyanate and to lissamine rhodamine B sulphonyl chloride. Frozen sections of lymph nodes from eighteen rabbits, A4-A4 and A5-A5 homozygotes and A4-A5 heterozygotes, were studied after exposure to the fluorescent antibody conjugates. The conjugates, each specific for antigenic determinants of 7S γ-globulin, reacted specifically with the cytoplasm of plasma cells and intrinsic cells of the germinal centres. The rabbit anti-A4 conjugate reacted only with lymph node cells of A4-A4 and A4-A5 rabbits; the rabbit anti-A5 conjugates reacted only with cells of A5-A5 and A4-A5 rabbits; the horse anti-rabbit γ-globulin conjugates reacted with cells of all three genotypes. By a variety of techniques, identical cellular localization of the two allotypes, A4 and A5, was found in the A4-A5 heterozygotes. Less than 1 per cent of the cells in any heterozygous lymph node section contained one allotype without the other. [ABSTRACT FROM AUTHOR]