Cytokines are a diverse group of soluble factors that mediate various cell functions, such as, growth, functional differentiation, and promotion or prevention of programmed cell death (apoptotic cell death). Cytokines, unlike hormones, are not produced by specialized glandular tissues, but can be produced by a wide variety of cell types, such as epithelial, stromal or immune cells.
The γc-family cytokines are a group of mammalian cytokines that are mainly produced by epithelial, stromal and immune cells and control the normal and pathological activation of a diverse array of lymphocytes. These cytokines are critically required for the early development of T cells in the thymus as well as their homeostasis in the periphery.