Structure of idiotopes associated with antiphenylarsonate antibodies expressing an intrastrain crossreactive idiotype
Abstract
We have explored the structural basis of idiotopes associated with the major idiotype (CRIA) of A/J anti-p-azobenzenearsonate antibodies, with emphasis on the regions of contact with anti-idiotypic antibody. The analysis was facilitated by a recent description of the three-demensional structure of the Fab portion of a CRIA-related antibody molecule. Direct binding measurements failed to reveal idiotopes associated exclusively with the L chain. However, the L chain participated in the formation of approximately 80% of the idiotopes recognized by polyclonal anti-Id. This indicates that multiple complementarity-determining regions (CDRs) participate in the formation of idiotopes. The affinity of anti-Id for CDRs on L chains must be appreciable but insufficient to permit direct binding (i.e., less than approximately 10(4) M-1). Approximately 20-35% of polyclonal anti-Id reacted with high affinity with H chains recombined with non-CRIA-related L chains. This interaction was found to involve the D region as well as one or both CDRs in the VH segment, again indicating the contribution of multiple CDRs. It is suggested that a typical idiotope may be similar in size to that of protein epitopes whose three-dimensional structures are know...Continue Reading