https://doi.org/10.1351/goldbook.13065
Any of a group of soluble small proteins released from a variety of cells, typically of the immune system, that affect cell behavior in an autocrine or paracrine fashion.
Note: Cytokines produced by lymphocytes are known as lymphokines; those produced by monocytes are called monokines. Other types of cytokines include chemokines, growth factors, colony-stimulating factors (CSFs), transforming growth factors, interferons, interleukins, and tumor necrosis factors.