Antigen-specific receptors on antibody-forming cells expressing light and heavy chain determinants

There has been controversy in the past about whether or not antibody-forming cells have antigen-specific receptors. Evidence is presented here which clearly demonstrates that some antibody-forming cells possess receptors while others show no evidence of receptors. Moreover, in this report the receptors are characterized in terms of their light and heavy chain immunoglobulin determinants. Receptors were found on ~50% of the direct PFC 6 days after one injection of sheep red blood cells (SRBC). On Day 4 of the secondary response only 20-33% of the direct PFC were found to possess receptors. Receptors could not be detected on indirect PFC in either the primary or secondary response. Results similar to the above were observed for the primary and secondary anti-hapten response to 3-nitro-4-hydroxy-5-iodophenyl acetic acid coupled to diphtheria toxoid (NIP-TOX). The receptors on the antibody-forming cells were shown to possess a class-specific heavy chain determinant (TgM) as well as two allotypic determinants, one a product of the a locus on the heavy chain and the other a product of the b locus on the light chain. The antigen-binding receptors were modulated to cap formation by antibody directed toward either light or heavy chain immunoglobulin determinants. The antigen-binding activity of the receptors was completely destroyed by trypsin.