Interleukin-6.

One of a group of related proteins made by leukocytes (white blood cells) and other cells in the body. IL-6 is made mainly by some T lymphocyte. It causes B lymphocytes to make more antibodies and also causes fever by affecting areas of the brain that control body temperature. IL-6 made in the laboratory is used as a biological response modifier to boost the immune system in cancer therapy. IL-6 is a type of cytokine. Also called interleukin-6.
Researchers have found that patients with plasma cell tumors have important abnormalities in other bone marrow cells and that these abnormalities may also cause excess plasma cell growth. Certain cells in the bone marrow called dendritic cells release a hormone called interleukin-6 (IL-6), which stimulates growth in normal plasma cells. Excess IL-6 production by these cells appears to be an important factor in development of plasma cell tumors.