THE MOLECULAR-BASIS OF THE HUMAN IMMUNE-SYSTEM

The human immune system is responsible for the discrimination between self and nonself and the orderly elimination of foreign antigen. At th e center of the immune response is the presentation of foreign antigen by antigen presenting cells (APCs) to T lymphocytes for coordination of host defense mechanisms. This complex operation requires: the recog nition, ingestion, digestion, and processing of antigen by APCs; the i nsertion of antigen-derived polypeptide into the appropriate HLA molec ule's antigen-binding groove; the docking of the APCs and T cells via complementary cell surface adhesion molecules; T-cell receptor recogni tion and binding of antigen in the context of the HLA molecule; the ex change or pro- and antiinflammatory cytokines between participating ce lls; and the amplification of the process as needed. Understanding the molecular basis of the normal human immune response affords investiga tors the ability to dissect its failings in disease states (e.g. autoi mmunity, immunodeficiency syndromes, and cancer) and the opportunity t o devise pharmaceutical interventions to benefit the host.