Interleukins (ILs) are a large group of cytokines that are produced mainly by leukocytes, although some are produced by certain phagocytes and auxiliary cells. Each IL acts on a specific, limited group of cells through a receptor specific for that IL. Interleukin 1 (IL1), originally known as lymphocyte activating factor (LAF), activates T cells and lymphocytes, which then proliferate and secrete interleukin 2. IL1 is primarily released from stimulated macrophages and monocytes, but also is