Detection of Interleukin-1β and Interleukin-6 in Human Multiple Myeloma by Fluorescent in situ Hybridization

Using fluorescent in situ hybridization together with cell surface marker staining, we studied the expression of mRNA of IL-6 and mRNA of IL-1β in bone marrow samples from human multiple myeloma patients. It is known that IL-6 can stimulate B cell growth and differentiation and recently it has been suggested that IL-6 is responsible for autocrine growth stimulation of myeloma cells and that IL-1 may play a role in bone resorption. These interleukins have previously been detected in the supernatants of cultured myeloma cells. Here we report the expression of IL-1β mRNA by plasma cells, T cells and macrophages according to morphology and immunologic marker analysis, suggesting that not only myeloma cells but other cell types can also contribute to the production of IL-1β and thus to bone-resorption. IL-6 mRNA could not be detected in plasma cells from bone marrow aspirates but were present in monocytes and T cells, suggesting that in vivo IL-6 stimulates the growth of myeloma cells in a paracrine instead of an autocrine way.