Monoclonal antibodies reactive with idiotypic and variable-region specific determinants on human immunoglobulins.

Monoclonal antibody JG-B1, specific for the human VKIIIb sub-subgroup of L chains, and JG-B4 specific for an idiotypic determinant on Glo, a monoclonal human IgM-VKIIIb anti-IgG, were produced and characterized. The VKIIIb determinant was detected on L chains alone and intact immunoglobulins with VKIIIb L chains. However, the idiotypic determinant was expressed only on IgM-Glo and required association of H and L chains. Binding of the immunogen Glo, to its antigen-IgG partially inhibited anti-idiotype and anti-VKIIIb binding. Cross-inhibition experiments demonstrated that intact pentameric IgM-Glo expressed one-half the number of idiotypic sites as VKIIIb determinants. However, Glo half-molecules expressed equal numbers of idiotypic and VKIIIb determinants. This is the first described monoclonal antibody produced by hybridoma technology which recognizes an antigenic determinant specific for a single variable region in intact immunoglobulin.