[CD28/B7 costimulating signal and its clinical significance]

It is necessary that the two signals are required in T cells activation. The first signal is specific, which T cell receptor could recognize and bind MHC molecule by antigen-presenting cells. Another one is nonspecific, which results from CD28/B7/CTLA4 molecules on T cells and antigen-presenting cells. The both of signals regulate function of T cells such as the activation, proliferation and secreting cytokines. CTLA4 showed the up-regulation in CD28/B7 costimulatory pathway as a negative signal. The immunosuppression could occur by blocking CD28/B7 pathway. It provided useful method for immunotherapy in the autoimmune diseases and graft-versus-host disease. But then, the activation of CD28/B7 could be valuable for the immune system recognizing and eliminating tumor cells.