transfer factor

Transfer factors are essentially small immune messenger molecules that are produced by all higher organisms. Transfer factors were originally described as immune molecules that are derived from blood or spleen cells that cause antigen-specific cell-mediated immunity, primarily delayed hypersensitivity and the production of lymphokines, as well as binding to the antigens themselves. They have a molecular weight of approximately 5000 daltons and are composed entirely of amino acids. Transfer factors were discovered by Henry Sherwood Lawrence in 1954. — Wikipedia