Present Status of Tumor Immunology in Clinical Gynecology

The function of the immune system is to protect the body from damage caused by invading microorganisms, that is, bacteria, viruses, fungi, and parasites. The humoral mechanism functions through plasma cells producing antibodies that control bacterial infections. Viruses, fungi and parasites are controlled through the thymus dependent T lymphocytes. It is now clear that cancers also invoke immunologic reactions in their hosts. Cancer cells, like bacteria and viruses have their own characteristic antigens. An antigen is defined as a substance, usually a protein or polysaccharide, that the body recognizes as foreign, and to whose presence it reacts by forming antibodies. Antigenic differences represent the first known qualitative distinction between cancer cells and their normal counterparts. These qualitative differences between normal and cancer cells had escaped other methods of investigation, but were revealed by immunological techniques that take advantage of the extraordinary power of discrimination of the immune defense mechanism itself. This mechanism is capable of distinguishing even minute differences between protein molecules, probably one different amino acid in a chain of several thousand. Burnet's clonal selection theory has become the central dogma of immunology. It can be summarized by saying that lymphocytes have been destined from time immemorial to identify a specific antigen. When the lymphocyte encounters that antigen it becomes a sensitized lymphocyte, and on contact with similar antigens again produces an immune response including the production of very potent pharmacologic agents called lymphokines. Immunodeficiency diseases are identified by increased frequency of infections in patients. The impaired immunity decreases the patient's protection against developing a malignancy. Autoimmunity is the reaction of the immune system against the body's own tissue. Autoimmune disorders as well as autoimmune diseases often follow a malignancy or predispose to its development. Hypersensitivity is related to the immunopathology that occurs when there is an exaggerated or inappropriate immune response. There are five types of hypersensitivity; and the cell mediated immunity and delayed hypersensitivity reaction is related to the protection of the body against invasion by malignant cells. Tumor markers are providing a method for indentifying the type of cancer and at present have a particularly important part in monitoring the therapy for the treatment of malignancies. One of the recent areas of interest in the field of immunology is that of biologic response modifiers: The body's inherent biochemical capacity for killing cancer cells plus the new genetic technology of biologic response modification or biomodulation for short. It is a new wave in cancer treatment. Recombinant DNA technology, commonly referred to as genetic engineering or gene splicing, has provided scientists with the tool for the biosynthesis and subsequent mass production of a significant number of biologicals. It has added an entirely new armamentarium to the diagnosis and therapy of malignant diseases.