Tumor immunology - When a cancer cell meets the immune cells

Tumor immunology consists of two essential concepts: immune surveillance, w hich specifies the host immune reactions against tumor cells, and tumor imm une escape, which refers to the tumor-cell evasion process against the host immune system. Effective antitumor immunity by the host immune surveillanc e is supposed to be dependent on the identification of tumor antigens. In t he process of malignant transformation, genetic mutations with aberrant exp ression of cancer-related genes and protein products are potentially immuno genic, which may serve as rejection antigens. Several scenarios are propose d to be responsible for tumor immune-escape mechanisms. The elucidation of the immune deficit against cancer progression has been a difficult task and no solitary mechanism explains the complicated cancer-host immune interact ions. Cancer cells may overcome immune surveillance through a common but ef fective pathway, either by changing the polarity of effector cells, thus do wn-regulating the proliferation of tumor-specific cytotoxic T cells, or alt ering the effector compositions of immune cells within the tumor milieu, or both. Understanding the interaction between cancer cells and host immune c ells within the tumor milieu is of importance for further clinical applicat ions of immunotherapy in cancer treatment.