Common idiotypes expressed on human, monoclonal, abnormal immunoglobulins and cryoglobulins with polyreaetive autoantibody activities

SUMMARY Several hutiian monoclonal immunoglobtilins with the same auloatitibody activity have been shown to have cross-reactive idiotypes (CRI). In this study, using polyclonal anti-idiotypic antibodies, we fotind that 28% of hutnan monoclonal immunoglobulins with polyreaetive autoantibody activity from myeloma. Waldenstrom's macroglobulinaemia and eryoglobulinaemia patients shared common idiotype(s). Furthermore, the latter were expressed on human and murine natural MoAbs (respectively in 12% and 22% of the clones tested) and on human IgG preparations used for therapeutic intravenous injections (IVlg) and which contain natural antibodies. These findings suggest that monoclonal immunoglobulins could arise from the proliferation of a clotie that normally produces a natural antibody. The existenee of common idiotype(s) between monoclonal immunoglobulins and IVIg could be relevant to the improvement noted after treatment with IVIg in patients suffering from peripheral neuropathies associated with monoclonal gammopathy.