Interleukin is a type of cytokine which acts specifically as a mediator between leukocytes. Interleukins are proteins secreted mostly by T cells lymphocytes and macrophages, inducing growth and differentiation of lymphocytes and hematopoietic stem cells. Interleukins play an important role in the regulation of lymphocyte function. Several known types are crucial constituents of the body's immune system.
Interleukins function as chemical messengers between cells. They mediate and control the immunologic and inflamatory response. The term "interleukin" was coined by Dr. Paetkau, University of Victoria.