Production of interleukin 2 in multiple myeloma.

The production of interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMC) was studied in 15 normal controls (NC) and 29 patients with multiple myeloma (MM), including 19 patients with active disease (i.e. diagnosis, relapse) and 10 with inactive disease (i.e. complete remission and off-treatment plateau). IL-2 was produced after stimulation of PBMC with PHA alone or with PHA and PMA. The role of suppressor factors/cells on IL-2 production was evaluated using indomethacin and irradiation of PBMC. T cells and T cell subsets (i.e. helper/suppressor T cells) were defined using standard monoclonal antibodies (T3, T4, T8). The production of IL-2 in active MM was similar to that of NC, using either PHA or PHA and PMA. However, a constant defect of prostaglandin-mediated suppressor cells was observed in patients in plateau, with a significant increase of IL-2 production in comparison to that of NC or active MM. IL-2 is an essential factor involved in T cell proliferation. Recent data demonstrate that it plays a role in B cell proliferation and differentiation into antibody-secreting cells. Suppression of antibody synthesis is a major feature of active (but not inactive) MM. The fact that IL-2 production was not affected in MM, in spite of an imbalance of some T cell subsets, is of major interest.