[Current concepts in the regulation of the immunologic response]

Regulation of the immunological response occurs at several levels which reflect the increasing complexity of our defense systems and of the immune apparatus. These regulation levels could be compared to the various floors of a building which are first explored and analyzed individually. They are (a) the development and differentiation of the immune system; (b) antigen presentation and genetic predispositions for a specific immune response; (c) idiotypic regulation of the immune response; (d) isotypic regulation and genetic control of the classes of antibodies produced, in particular IgE; (e) immunological regulation through various lymphocyte subpopulations; (f) regulation of the reactivity of inflammatory cells and (g) neuroendocrine regulation of the immune system. Any one of these chapters or levels may be presented and discussed as such, and are at the present time relatively well understood. It is more difficult, however, to evaluate the vertical communications between the various levels of regulation and the relative importance of the individual regulating systems in the development of a global immune response by the organism.