Antigenic properties of human IgG Kappa and IgG lambda myeloma plasma cells.

In 12 patients with multiple myeloma of type IgG, lymphocytes were isolated from the peripheral blood and sensitized to a pool of normal allogeneic cells or to allogeneic or autologous myeloma plasma cells. They were tested for cytotoxicity in a 51Cr release assay. Pool-sensitized cells were capable of lysing autologous myeloma cells of type IgG Kappa (IgGK), but not of type IgG Lambda (IgG delta). Sensitization of lymphocytes to allogeneic myeloma cells of type IgG delta led to lysis of both autologous and allogeneic myeloma cells of type IgG delta and IgGK, whereas sensitization to allogeneic IgGK myeloma cells failed to generate effector cells capable of lysing autologous or allogeneic myeloma cells. These results indicate that there exist distinct stimulating antigens and both distinct and common (cross-reacting) target antigens on human IgGK and IgG delta myeloma plasma cells.