Cytokines

Cytokines are small secreted proteins released by a broad range of cells, including phagocytes that have engulfed pathogens and cells that have been activated by pathogens.Cytokines act as cell-signalling molecules informing other phagocytes and other immune cells that the body is under attack.Cytokines may act on the cells that secrete them, on nearby cells, or in some instances on distant cells.Cytokines can also move to the site of infection or inflammation and increase the body temperature and stimulate the specific immune system.Cytokines are important in regulating immune responses and inflammation. They regulate the balance between humoral and cell-based immune responses and can inhibit or stimulate the release of other cytokines.Cytokines alter cell functions by upregulating or downregulating genes and their transcription factors, resulting in the production of other cytokines, an increase in the number of surface receptors for other molecules, or the suppression of their own effect by feedback inhibition.Cytokines have considerable redundancy; many cytokines appear to share similar functions.