Abstract
The nature of the immunoglobulin (Ig) G found associated with the neoplastic B lymphocytes in chronic lymphocytic leukemia that also express Igm and IgD had been investigated by absorption studies using anti-idiotypic antibodies raised against cell surface IgM from five patients. In all five cases, although cellular IgM and IgD behaved as idiotypic, the IgG did not. Thus the IgG frequently found associated with lymphocytes at this stage of differentiation is likely, at least in many cases, to be of extrinsic origin.