Reconstitution from subunits of the hapten binding sites and idiotypic determinants of mouse anti-phosphorylcholine myeloma proteins.

Reconstitution experiments were employed to investigate the structure of the hapten binding sites and idiotypic determinants of mouse myeloma proteins with antibody specificity for phosphorylcholine. Quantitative reconstitution of both the phosphorylcholine binding affinity and idiotypic reactivity of these immunoglobulins was shown to require specific heavy and light chain combinations. Interaction of myeloma protein with hapten (phosphorylcholine or choline) had no effect on the expression of the idiotype. The subunits of the immunoglobulins possessing in common an idiotype and affinity for phosphorylcholine reconstituted indistinguishable antibodies. In addition, it was shown that the light chains of the proteins belong to the same κ subgroup. Since these indistinguishable immunoglobulins are found repeatedly, they may represent the expression of the same heavy and light chain variable region genes out of a small number present in the BALB/c germ-line.