Switched allotype expression in an immunoglobulin-nonsecreting rabbit lymphoid cell line fused with rabbit gangliocytes

Abstract

The Simian virus 40-transformed rabbit spleen cell TRSC-1 synthesizes intracellular whole IgG molecules of the alb4 allotype. Two hypoxanthine-guanine phosphoryl transferase-deficient mutants were derived from this line. One of these, TRSC-1-8, was used in somatic cell fusion experiments together with gangliocytes from a rabbit immunized against beta-galactosidase. Out of nineteen hybrid clones surviving in selective medium, only one, L17, was shown to produce free gamma chains which express the a2 allotype of the donor rabbit rather than the al marker of the parents TRSC-1-8 line. The inability to restore IgG secretion in hybrids suggests that dominant regulatory controls are exerted by the TRSC-1 genome on Ig reduction. This supports the notion that the TRSC-1 line originated from a splenocyte that had not reached the final plasmocyte differentiation stage at the time of viral transformation.