Autocrine signalling

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Autocrine signalling is a form of signalling in which a cell secretes a chemical messenger (called the autocrine agent) that signals the same cell.

An example of an autocrine agent is the cytokine interleukin-1 in monocytes. When this is produced in response to external stimuli, it can bind to cell-surface receptors on the same cell that produced it.

Another example occurs in activated T cell lymphocytes, i.e. when a T cell is induced to mature by binding to a peptide:MHC complex on a professional antigen presenting cell and by the B7:CD28 costimulatory signal. Upon activation, "low affinity" IL-2 receptors are replaced by "high affinity" IL-2 receptors consisting of α, β, and γ chains. The cell then releases IL-2 which binds to its own new IL-2 receptors, causing self-stimulation and ultimately a monoclonal population of T cells. These T cells can then go on to perform effector functions such as macrophage activation, B cell activation, and cell-mediated cytoxicity.