Objective: To explore the source cells of interleukin-6 (IL-6) among bone marrow cells in multiplemyeloma (MM). Methods: Expressions of IL-6 in bone marrow mononuclear cells (BMMNCs) were detected using double labeled immunofluorometry, and the IL-6 activities in the supernatants of co-culture system of myelomacell line KM3 and bone marrow stromal cells (BMSCs) were measured using B9 cell proliferation test. ResultS: IL6 molecules were expressed not only in cytoplasndc γ-globin positive cell but also in type I collagen or von Willebrand Factor(vwr)positive cells. After fixation, both myeloma cells and BMSCs hardly secreted IL-6. IncreasedIL-6 activities were found in the supernatants after co-culture of unfixed my8loma cell line KM3 and fixed BMSCsor of fixed KM3 cells and unfixed BMSCs. Furthermore, BMSCs from MM patients induced KM3 cells to secretsignificantly more IL-6 in the supernatants than in BMSCs did controls (P<0. 01). Couclusiou: Both the BMSCsand myeloma cells secret IL-6 simultaneously in MM. Their interaction with each other promotes IL-6 over production. Both autocrine and paracrine mechanisms of IL-6 dysregulated expression are involved in the pathogenesisof MM.
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