[Preferential proliferation of natural killer cells with bone marrow mononuclear cells in multiple myeloma]

We examined proliferation of natural killer (NK) cells in 10 day mixed culture of peripheral blood mononuclear cells (PBMC) from healthy subjects with irradiated bone marrow mononuclear cells (BMMC) with multiple myeloma. In culture, NK cells increased with 9.5-fold. However, no increase was observed in T cells. The NK cell proliferating activity of PBMC stimulated with BMMC was higher than that of IL-2. NK cells at a purity of 90% or higher purity were collected from 10 day culture. Proliferation of these NK cells was stimulated by the addition of IL-2 but was suppressed by the addition of antibody coated erythrocyte (EA). IFN-gamma production was negligible in cultures of these NK cells alone but was marked in cultures with EA stimulate IFN-gamma production. Next, the NK cell obtained as above showed marked NK activity against K 562 cells, and this activity was further enhanced by the addition of IL-2. Also, while NK cells, these NK cells had some activity against Daudi cells and it was enhanced by the addition of IL-2. These results also suggest the presence of unknown cytokines with NK cell proliferating activities in the bone marrow of patients with multiple myeloma.