any of various soluble proteins, as interferon, that are secreted by T cells interacting with an antigen and that help fight infection
See lymphokine in American Heritage Dictionary 4
(lĭmˈfə-kīnˌ)
noun
Any of various substances released by T cells that have been activated by antigens. They function in the immune response through a variety of actions, including stimulating the production of nonsensitized lymphocytes and activating macrophages.