3 NEW CROSS-REACTING IDIOTOPES AS MARKERS FOR THE PRODUCTS OF 2 DISTINCT HUMAN V(H)3 GENES EXPRESSED IN THE EARLY REPERTOIRE

This article describes characterization of three new cross-reacting id iotopes, as recognized by mouse MoAbs, on human antibodies utilizing V (H)3 genes that are expressed in the early repertoire. Two of the mous e MoAbs (3H7 and 3H1) were raised against a human MoAb utilizing the D P47 (VH26) V(H)3 gene, whilst the third (7B4) was raised against a DP4 6 (GLSJ2) gene product. Evidence for the anti-idiotypic specificity of the mouse MoAbs was provided by their reactivity with the immunizing IgM, but not with Fc mu, and by their specific inhibition of the bindi ng between each immunizing antibody and its antigen. The three anti-id iotypic MoAbs were shown to be V-H-specific reagents by the independen ce of their reactivity upon the L-chain type, or the antigenic specifi city of the human MoAbs tested. Specificity of each mouse MoAb for V(H )3 gene-products was demonstrated by its sole cross-reactivity with V( H)3 proteins. Each anti-Id had a different reactivity pattern with a p anel of MoAbs utilizing different V(H)3 genes. By relating the V-H seq uences of the tested V(H)3 proteins to their germline counterparts, 3H 7 and 3H1 appeared to be specific for DP47-encoded proteins, although 3H1 had weak cross-reactivities with a few other V(H)3 gene-products. 7B4 appeared to be specific for antibodies utilizing DP46-related gene s. Both 3H7 and 3H1 were also completely different to B6 and D12, two previously described MoAbs that also recognize V(H)3 proteins. Althoug h 7B4 was similar to B6 and D12 in its binding to DP46-related gene pr oducts, B6 and D12 additionally recognized non DP46-related proteins a nd were thus different to 7B4.