Cytokines are chemical messengers that control immune responses. They are secreted by white blood cells, T cells, epithelial cells and some other body cells. There are at least 17 different kinds of interleuken and 3 classes of interferon called alpha, beta and gamma and various subsets. Interleukens and interferons are called “cytokines” and there are two general groupings, Th1 and Th2. Th1 (T-cell Helper type 1) promote cell-mediated immunity (CMI) while Th2 (T-cell Helper type 2) induce humoral immunity (antibodies).