Tumor rejection antigens and tumor specific cytotoxic T lymphocytes.

In several tumor models and in certain types of human malignancies, T cell mediated immune responses can be involved in the host's defences against cancer. Adoptively transferred tumor-specific T cells can mediate complete tumor regression in several animal models and the first effective therapeutic interventions with adoptively transferred (virus-specific) CTL in man have been reported. With the identification of tumor rejection antigens new antigen specific therapeutic approaches come into sight. The development of anti-tumor vaccines based upon known tumor rejection antigens might take off rapidly in the near future, since only the first few tumor rejection antigens of an enormous potential have been reported. This development will go hand in hand with the utilization of cytokines in these vaccines. Cytokines might promote T cell activity or antigen presentation, but can also be used to counteract tumor immune escape mechanisms. Escape from immune surveillance and T cell mediated elimination by tumor cells might account for the failure of the immune system to eradicate or prevent the outgrowth of many types of tumors. The identification of tumor rejection antigens and tumor-specific immune responses, together with a better understanding of the mechanisms by which tumors escape from T cell mediated immunity brings fresh encouragement in the field of tumor immunology.