The Production of Interferon by Malignant Plasma Cells from Patients with Multiple Myeloma

Abstract To help define the types of immunocytes capable of producing interferon, bone marrow cultures from patients with multiple myeloma were studied. Such cultures contained large numbers of plasma cells, the end stage in the differentiation of bone marrow-derived or B lymphocytes. Quantitative studies of in vitro interferon and immunoglobulin synthesis rates were performed. The results were as follows: a) Interferon was detected within 24 hr in supernatant fluids of cultures from 10 of 12 patients with myeloma studied. These included six patients with IgG myeloma, two with IgA myeloma, one Amyloid myeloma, and one κ light chain myeloma. b) The amount of interferon produced was unrelated to the immunoglobulin synthesis rate, total body tumor cell number, sensitivity of the tumor to chemotherapy, or the clinical status of the patient. c) The plasma cell origin of such interferon was demonstrated by a study in which enrichment of the myeloma cells by gradient techniques resulted in increased interferon production. No interferon was detected in cultures in which there were low or no plasma cells, i.e., those prepared from peripheral blood leukocytes of patients with myeloma, or bone marrow from normal individuals. Interferon synthesis was not detected from bone marrow cells from two patients with Waldenstrom's macroglobulinemia.