Regulation of azophenylarsonate-specific repertoire expression. II. Fine specificity and isotype heterogeneity of anti-arsonate antibodies

Abstract

This report investigates the isotope and binding site heterogeneity of IgG anti-azophenylarsonate (ARS) monoclonal antibodies derived from splenic fragment cultures of nonimmune and immune A/J mice. By using five arsanilic acid derivatives in a hapten inhibition assay to determine fine specificity, the secondary ARS-specific repertoire was found to be extremely heterogeneous, with 52 unique patterns among the 81 antibodies analyzed. CRIA+ and CRIA+/- clonotypes were as heterogeneous as CRIA- antibodies, but a majority of CRIA+/- clones maintained a characteristic relative affinity for two of the haptens, p-arsanilic acid (p-ARS) and p-azobenene arsonic acid-N-tyrosine (ABA-tyr), which was identical to the prototype CRIA+ hybridoma protein R16.7. We also observed that the average relative affinity of CRIA- antibodies from immunized donors was higher than nonimmune mice with respect to p-ARS and ABA-tyr, and that there was a further increase in avidity to ABA-tyr over time after immunization. In contrast, no affinity maturation occurred among the CRIA+ and CRIA+/- clones. Rare antibodies were also identified within the nonimmune repertoire that had higher relative affinities than R16.7. Despite this, a greater proportion of CRIA+ and CRIA+/- clones produced IgG antibody in vitro. Thus, the predominance of CRIA+ antibodies in the ARS-specific immune repertoire and the preferential differentiation of CRIA+ precursor cells to IgG secretors cannot be entirely explained by the avidity of this clonotype family for p-ARS or ABA-tyr.