Similar idiotypic specificity for the membrane IgD and IgM of human B lymphocytes.

Certain cases of chronic lymphocytic leukemia possess monoclonal bands in the serum. Idiotypic antibodies to the isolated IgM protein of one such case demonstrated that the leukemic lymphocytes carried the identical specificity on their lymphocytes. Both the lymphocyte IgM and the IgD possessed this same specificity. This was demonstrated best through the use of rhodamine-conjugated Fab fragments of IgM- and IgD-specific antisera which were both capped by the idiotypic antiserum.