INTERLEUKIN-4 AND TUMOR-NECROSIS-FACTOR-ALPHA PRODUCE NON ISOTYPE-SPECIFIC PARTIAL DIFFERENTIATION OF PERIPHERAL-BLOOD B-CELLS IN MYELOMA

In a previous study, culture oi peripheral blood mononuclear cells (PB MC) from myeloma patients with interleukin(IL)-4 and tumour necrosis f actor(TNF)-alpha resulted in the appearance of clonal plasma cells, th us suggesting the presence of circulating myeloma cell precursors in t he peripheral blood. Using the same cytokine combination, we cultured PBMC and purified peripheral blood B-cells from myeloma patients. In n early all cases, partial differentiation of B-cells occured but, simil arly to results for normal controls, both kappa and lambda light chain (L.C.) cytoplasmic positive lymphoid and lymphoplasmacytoid cells wer e detected rather than clonal plasma cells. These results suggest that IL-4 and TNF-alpha cause partial differentiation of residual normal p olyclonal B-cells rather than of circulating myeloma cell precursors i n the peripheral blood of myeloma patients.