A cytokine (IL-1α, LAF, MCF; IL-1β, interferon-β-inducing factor, OAF, catabolin) involved in the activation of both T and B cells in response to antigens or mitogens, as well as affecting a wide range of other cell types. IL-1α (159 aa) is produced by keratinocytes and IL-1β (153 aa), the predominant form in humans, is mostly produced by monocytes. Although the two forms, encoded by different genes, have only 27% homology, they bind to the same receptor. The precursors lack a signal sequence. An endogenous IL-1 receptor antagonist, IL-1ra (152 aa, with a standard signal sequence), binds to the receptor without eliciting a response; soluble and intracellular forms are known. The receptor (p80, CD121a, 569 aa) is a member of the immunoglobulin superfamily and is expressed predominantly on T cells and cells of mesenchymal origin. See also catabolin; endogenous pyrogen.
Subjects: Medicine and Health — Chemistry.