Transient IgA-lambda paraproteinemia during treatment of acute myelomonoblastic leukemia.

Monoclonal plasma cell proliferation with secretion of IgA-lambda and free lambda light chains during a phase of bone marrow aplasia following intensive chemotherapy was observed in a patient suffering from acute myelomonoblastic leukemia. The clonal expansion and regression was investigated at the cellular level by immunofluorescence using an antiserum against the idiotype of the paraportein. Although a large panel of common antigens was used for testing, no antibody activity of the paraprotein could be demonstrated.