Cytokines play an essential role in the final differentiation of B-cells into Ig-secreting cells Involved in lymphocyte and monocyte differentiation. Interleukin-6 (IL-6) is a multifunctional cytokine with a wide variety of biological functions. IL-6 is implicated in the final differentiation of B-cells into immunoglobulin-secreting cells, myeloma and plasmacytoma growth, nerve cell differentiation, and activation of hepatocytes and mitogen-stimulated helper T cells.