Cell-Mediated Immunity to Plasma Cell Myeloma: Specific Inhibition by a Serum Factor Adhering to Effector Lymphocytes

Tumor-directed immune reactivity was studied in ten patients with plasma cell myeloma by the lymphocyte histogenesis method. Three patients showed positive reactions to their own myeloma cells. In two of them this reactivity was detected only among extensively washed lymphocytes in the presence of normal serum and specifically inhibited by the patients' own serum. A supernatant obtained from the lymphocyte washing in one patient revealed the same abnormal immunoglobulin which circulated in the plasma of this patient. This suggests but does not prove that the abnormal immunoglobulin on the surface of myeloma cells may carry foreign antigenic determinants which can evoke a cellular immune response in the host while its circulating counterpart may specifically block this immune response by binding to the surface of the effector lymphocytes.