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Any of a class of naturally occurring proteins important in regulation of lymphocyte function. Several known types are recognized as crucial constituents of the body's immune system (seeimmunity). Antigens and microbes stimulate production of interleukins, which induce production of various types of lymphocytes in a complex series of reactions that ensure a plentiful supply of T cells that fight specific infectious agents.
This entry comes from Encyclopædia Britannica Concise. For the full entry on interleukin, visit Britannica.com.