Nonsecretion of myeloma protein in spite of an increase in tumor burden by chemotherapy.

A unique case of IgA kappa myeloma is presented. While the myeloma cells had secreted a large quantity of IgA kappa monoclonal protein, they were induced to stop secreting the monoclonal protein by cyclophosphamide and vincristine, in spite of a remarkable increase in tumor burden. The absence of intracytoplasmic IgA kappa was clearly evidenced by the immunofluorescence technique using anti-IgA and anti-kappa monoclonal antibodies.