interleukins (IL)

interleukins (IL)

a group of polypeptide cytokines that carry signals between cells in the immune system. The molecules are produced by the cells and bind to specific receptors on the surface of appropriate target cells.

Among the interleukins so far characterized are: IL1, which is released from macrophages, hence also called monokine, and affects T lymphocytes; IL2, produced by T lymphocytes and affects T lymphocytes, also known as T lymphocyte growth factor; IL3, produced by B lymphocytes and affects B lymphocytes, also known as B lymphocyte growth factor; IL4, produced by helper T lymphocytes and acts on B lymphocytes; IL5, produced by T lymphocytes and acts on eosinophils; IL6, produced by mononuclear phagocytes and acts on hepatocytes and B lymphocytes; IL7, secreted by bone marrow and thymic stromal cells and induces stem cells to differentiate into progenitor T and B lymphocytes; IL8, secreted by macrophages and endothelial cells and chemotactically attracts neutrophils and induces their adherence to vascular endothelium and extravasation; IL9, secreted by T helper lymphocytes and acts as a mitogen for these cells; IL10, secreted by T helper 2 lymphocytes and acts on macrophages to suppress cytokine production and thus indirectly reduce cytokine production by T helper 1 lymphocytes; IL11, secreted by bone marrow stromal cells and promotes differentiation of progenitor B lymphocytes and megakaryocytes; induces hepatocytes to synthesize acute phase proteins and supports growth of plasmacytomas; IL12, produced by macrophages and B lymphocytes and acts synergistically with IL2 to induce cytotoxic T lymphocytes; also stimulates proliferation of natural killer (NK), lymphokine activated killer (LAK), and T helper 1 cells; IL13, produced by T helper lymphocytes and inhibits activation and release of inflammatory cytokines by macrophages; an important regulator of the inflammatory response. Interferons α, β, γ are also interleukins. There are others.