The immune system and cancer

The hypothesis of immunologic surveillance of neoplasia is predicted on the theory that the immune system is capable of discriminating self from forei gn antigens, and that tumour-specific antigens are regarded by the immune s ystem as nonself. An alternate view proposed was that the immune system has evolved to detect danger by employing 'professional' antigen-presenting ce lls as sentinels of tissue distress. The field of tumour immunology has witnessed short bursts of great exciteme nt followed by longer periods of pessimism. Enthusiasm appears to be rising again as many tumour-associated antigens have been identified and their us e in vaccines is currently the subject of many clinical trials. The develop ment of genetic engineering has allowed the conversion of anti-tumour mouse monoclonal antibodies into mouse-human chimerized antibodies and humanized reagents, which are undergoing clinical trials. Although 'immuno-genethera py' appears to be a promising approach, much work still needs to be done to understand the mechanisms involved so that efficacious treatment modalitie s can be designed.