Comparative studies on monotypic IgMlambda and IgGkappa from an individual patient. I. Evidence for shared VH idiotypic determinants.

A comparative idiotypic antigenic analysis of an IgMlambda and an IgGkappa paraprotein obtained from sera of an individual patient, Br, revealed the presence of very similar idiotypic determinants associated with the VH regions of the Br mu- and gamma-chains. In addition, the IgGkappa protein expressed light (L) chain-associated idiotypic determinants which were not evident on the IgMlambda protein or its isolated L chains. Extensive tests of specificity revealed that the shared VH idiotypic determinants were not present in large weight amounts of heterologous nonspecific IgM and IgG, nor on Ig molecules contained in a large number of normal and myeloma sera.