IMMUNOLOGY AND MEDICINE
Immunological concepts have found ample applications in medicine in areas related to di-agnosis, treatment, prevention, and pathogenesis.
1. The exquisite specificity of the antigen-antibody reaction has been extensively applied to the development of diagnostic assays for a variety of substances. Such applications received a strong boost when experiments with malignant plasma cell lines and normal antibody-producing cells resulted serendipitously in the discovery of the technique of hybridoma production, the basis for the productio of monoclonal antibodies, which have had an enormous impact in the fields of diagnosis and immunotherapy.
2. Immunotherapy is a field with enormous possibilities, although the results of many attempts at the therapeutic application of immune strategies have been disappointing. Nevertheless, stimulation of the immune system with cytokines (particularly IL-2), downregulation of inflammatory reactions with anticytokine antibodies or recombinant soluble receptors, treatment of leukemia with monoclonal antibodies and immunotoxins, and prevention of graft rejection with monoclonal antibodies are but a few examples of successful medial applications of immunotherapy protocols.
3. The study of children with deficient immune system development (immunodeficiency disease) has provided the best tools for the study of the immune system in humans, while at the same time giving us ample opportunity to devise corrective therapies. The acquired immunodeficiency syndrome (AIDS) underscored the delicate balance that is maintained between the immune system and infectious agents in the healthy individual and has stimulated a considerable amount of basic research into the regulation of the immune system that may have enormous implications not only in the treatment of HIV/AIDS, but in many other areas of medicine.
4. The importance of maintaining self-tolerance in adult life is obvious when we consider the consequences of the loss of tolerance. Several diseases, some affecting single organs, others of a systemic nature, have been classified as autoimmune diseases. In such diseases the immune system reacts against cells and tissues; this reactivity can either be the primary insult leading to the disease or represent a factor contributing to the evolution and increasing severity of the disease. New knowledge of how to induce a state of unresponsiveness in adult life through oral ingestion of antigens has raised hopes for the rational treatment of autoimmune conditions.
5. Not all reactions against nonself are beneficial. If and when the delicate balance that keeps the immune system from overreacting is broken, hypersensitivity diseases may become manifest. Common allergies, such as asthma and hay fever, are prominent examples of diseases caused by hypersensitivity reactions. Manipulation of the immune response to induce a protective rather than harmful immunity was first attempted with success in this type of disease.
6. Research into the mechanisms underlying the normal state of tolerance against nonself attained during normal pregnancy continues to be intensive, since this knowledge could be the basis for more effective manipulations of the immune response in patients needing organ transplants and for the treatment or prevention of infertility.
7 The concept that malignant mutant cells are constantly being eliminated by the immune system (immune surveillance) and that malignancies develop when the mutant cells escape the protective effects of the immune system has been extensively debated, but not quite proven. However, anticancer therapies directed at the enhancement of antitumoral responses continue to be evaluated, and some have met with encouraging results.