any of a group of molecules, including interferon, interleukin, and tumor necrosis factor, secreted by certain cells of the immune system which modulate certain cell functions associated with immune response
See cytokine in American Heritage Dictionary 4
cy·to·kine
noun
Any of several regulatory proteins, such as the interleukins and lymphokines, that are released by cells of the immune system and act as intercellular mediators in the generation of an immune response.
Origin: cyto- + Greek kīnein, to move; see kinin .