INTERLEUKINS

Interleukins are a group of cytokines (secreted signaling molecules) that were first seen to be expressed by white blood cells (leukocytes, hence the -leukin) as a means of communication (inter-). The name is something of a relic though (the term was coined by Dr. Paetkau, University of Victoria); it has since been found that interleukins are produced by a wide variety of bodily cells. The function of the immune system depends in a large part on interleukins, and rare deficiencies of a number of them have been described, all featuring autoimmune diseases or immune deficiency.
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Interleukin /in·ter·leu·kin/ a generic term for a group of multifunctional cytokines that are produced by a variety of lymphoid and nonlymphoid [more]Interleukins - Community and Resources

Noun
1. any of several lymphokines that promote macrophages and killer T cells and B cells and other components of the immune system
(hypernym) lymphokine

Substances used in biological therapy. Interleukins stimulate the growth and activities of certain kinds of white blood cells.

Molecules which relay signals between cells of the immune system.