Interleukin (IL 2),which is a cytokine secreted by activated T cells, plays important roles in vivo. The abnormal expression of IL 2 and/or its receptor(IL 2R)will result in immunopathological changes, such as autoimmune diseases. Therefore, the antagonists of IL 2/IL 2R are an attractive target for the therapeutic agents of autoimmune diseases and allograft rejection in organ transplant. Interleukin 2 receptor α chain (IL 2Rα) is expressed only on the surface of abnormal T cells in patients w...