Inter-relationship between immunoglobulin idiotype and metatype

Allogenic anti-metatype (Met) and anti-idiotype (Id) reagents were elicited to the liganded and nonliganded states, respectively, of a high affinity murine monoclonal anti-fluorescein IgM antibody. Through comparisons of the relative immunogenicity and specificity patterns of the resulting antibody reagents, interpretations regarding the relationship between metatopes and idiotopes were rendered. Anti-Id specificity was measured in terms of the degree of ligand inhibition to two different forms of the fluorescyl hapten (i.e. free ligand and conjugated to a macromolecule). Idiotypic analysis of 18-2-3 H and L chains (immunoglobulin heavy and light chains) demonstrated that recognition of 18-2-3 Id determinants required recombination of H and L chains. Anti-Met reagents were evaluated relative to the liganded and nonliganded states of the IgM antibody. Binding studies indicated anti-Met specificity for liganded or affinity labeled Mab (monoclonal antibody) 18-2-3, but not for nonliganded 18-2-3 or the fluorescein ligand. The affinity labeled metatypic state provided the optimum immunogen yielding an antibody reagent which was rendered specific for the liganded state upon absorption with appropriate immunoglobulin reagents. Antibodies specific for affinity labeled 18-2-3 did not react with liganded 4-4-20, an IgG2a monoclonal anti-fluorescein antibody of similar high affinity but unrelated idiotypically. Results were discussed in terms of intrasite, proximal-site and distal-site epitopes.