Specificity of antibody and helper T-cell responses to the isologous myeloma protein W3129 and its subunits

Abstract

The specificity of BALB/c antibodies and T h, elicited by BALB/c myeloma protein W3129 (α, κ) and its subunits was studied. Antibodies were detected with RIA and ELISA techniques. T h were demonstrated by their ability to augment a secondary anti-NIP antibody response in a Mitehison type assay of adoptive immunity. The major proportion of antibodies elicited by the complete W3129 was directed to an idiotypic determinant(s) that depended on assembled H + L chains. The determinant(s) was probably located in or near the antibody combining site because binding was hapten-inhibitable. A second minor antibody population bound an idiotypic determinant(s) on V H W3129 expressed on isolated H-chain as well as on the complete myeloma protein. A third and very weakly reactive set of antibodies was specific for a C α antigenic site(s) which was expressed much more efficiently on free than on assembled α-chains. The antibody response to free κ W3129 was directed to idiotypic determinants that were inaccessible in the complete molecule. By contrast, free κ W3129 elicited T h that responded to an idiotypic determinant(s) on V k W129; the determinant(s) was expressed on both the isolated chain and the complete W3129, suggesting that T h responded to an idiotope not recognized by B-cells. Priming with free α W3129 failed in four out of five experiments to induce T h that responded to the complete W3129, demonstrating that a major difference existed between V H and V L of W3129 regarding their immunogenicity for T h. Nevertheless, free α W3129 did elicit antibody responses that displayed high reactivity with the complete molecule, indicating that certain serologically defined antigenic sites on the surface of W3129 are also expressed on isolated α W3129 Thus, certain differences were detected as to the specificities of T h and B-cells for W3129 and its subunits since they recognized separate idiotopes located in the V L- or V H-region, respectively. The pattern of T h recognition of W3129 resembled that of another isologous myeloma protein, M315, but was unlike that of a third, J558, previously described from this laboratory.