Effect of interleukin-2 on the ex vivo growth of human myeloma cells.

Short-term cultures containing bone marrow mononuclear cells from multiple myeloma patients secrete monoclonal immunoglobulin- and beta 2-microglobulin into the supernatant, which can be measured quantitatively in an enzyme-linked immunosorbant assay. In this system, the addition of interleukin-2 was shown to induce tumor cell regression in the cultures from 10 out of 14 multiple myeloma patients in a dose-dependent manner. Marker analyses of culture cell populations indicate that OKT3 antibody or interleukin-2 did not directly act on the malignant clone but augmented autologous T lymphocytes, which were responsible for the regression of tumor cells in the cultures.