Immunochemical and molecular characterization of regulatory idiotopes expressed by monoclonal antibodies exhibiting or lacking beta 2-6 fructosan binding activity.

Abstract

Hybridomas secreting antibodies bearing the ABPC48 (A48) regulatory idiotype (Id) were generated from BALB/c mice treated at birth or as adults with minute amounts of anti-A480Id antibodies. The majority of these antibodies were recognized by the syngeneic monoclonal anti-A48-Id and anti-UPC-10-Id antibodies, IDA10 and 10-1, respectively. In Northern blotting experiments, most of these hybridomas were shown to use VH (H chain variable region) genes related to the 441-4 germline VH gene that encodes the A48 VH region. Hybridization was detected between polyadenylated H chain mRNA, isolated from the majority of the hybridomas, and the VH441-4 probe. Southern blots confirmed these results by showing a rearrangement of VH441-4-related sequences to the JH (H chain joining segment) clusters on these same hybridomas. The antibodies from all of the hybridomas that derived from neonatal mice and half of those derived from adult mice showed specificity for frutosan determinants that, in most cases, was different from the .beta.2-6 fructosan linkage specificity of A48. Several of the non-fructosan-binding hybridomas generated from the adult mice and the MOPC-173 myeloma demonstrated a clear specificity for the .beta.1-6-D-galactan determinant. Of 4 galactan-binding myeloma proteins studied. XRPC 44 alone shared idiotype with the UPC-10 myeloma. A possible clonal crossreactive regulation mediated by regulatory idiotypes is suggested. The crossreactive regulation concept is discussed.