In vitro suppression of immunoglobulin allotype synthesis by antibody specific for heavy chain determinants

Abstract

Spleen cells (SpC) from normal adult rabbits heterozygous at the a locus for heavy chain allotypes or at the b locus for kappa light chain allotypes were incubated for 24 hr in vitro with various antibodies (Ab) specific for allotypic determinants on the Fd fragment of immunoglobulin (Ig). After washing, the cells were reincubated in vitro for an additional 4 days to ascertain the effect of these various Ab preparations on subsequent Ig production. Inhibition of indirect radioprecipitation was used as a sensitive assay for the allotypic markers on Ig molecules in the tissue culture supernatant fluids. SpC from rabbits heterozygous for allotypic determinants of the Fd fragment, i.e., of genotype a 1 a 3, were incubated with anti-a1 or anti-a3 and this led to a suppression in the production of the corresponding allotype without a discernible effect on the allelic allotype. Suppression of Ig production was also achieved by incubation of SpC with class-specific anti-IgM but not with class-specific anti-IgG Ab, which suggests that the cells that are suppressed interact with the Ab via an IgM molecule, which is an integral part of the cell membrane.