Interleukin-1 (IL-1), originally known as Lymphocyte Activating Factor (LAF), activates T cells and lymphocytes, which then proliferate and secrete interleukin-2.1 IL-1 is primarily released from stimulated macrophages and monocytes, but is also released from several other cell types,2 and is thought to play a key role in inflammatory and immune responses.3 Other synonyms for IL-1 include: Endogenous Pyrogen (EP), Mitogenic Protein (MP), Helper Peak-1 (HP-1), T Cell Replacing Factor III (TRF III or TRFH), B cell Activating Factor (BAF) and B Cell Differentiation Factor (BDF).4 The two closely related agents, Interleukin-1α (IL-1α) and Interleukin-1β (IL-1β) bind to the same cell surface receptor, elicit nearly identical biological responses and yet share 25% homology in their amino acid sequence. Recombinant rat IL-1β is a 17.3 kDa protein containing 153 amino acid residues.
