T cells and immunosuppression in tumor bearing state

T cell responses regulating antigen-specific immune response are modulated to result in proliferation, apoptosis, or anergy by subtle differences of antigen-peptide, or costimulatory signals through adherent molecules. In tumor immunology there has been recent progress especially in the identification and cloning of tumor specific antigens recognized by cytotoxic T cells. On the other hand, it is known that in the tumor hearing state several mechanisms have caused the suppression of immune response regulated by T cells. Recently, we revealed that oxidative stress by activated macrophages in the tumor hearing state induces structural abnormalities of T cell receptor complex and suppresses the antigen-specific T cell response.