Vaccinology, immunology, and comparative pathogenesis of measles in the quest for a preventative against AIDS.

Current approaches to the prevention and control of AIDS by vaccines and by chemotherapy have failed to provide satisfactory solutions to this important medical problem and have failed, in addition, to provide definitive guidelines for future research endeavor. Vaccine research must and will continue but it is possible that a safe and effective vaccine may never be developed and it may be timely to explore, in addition, alternative means for immunological intervention in AIDS. Both immunoprophylactic and immunotherapeutic efforts might be assisted by manipulating the T helper 1 (Th1) and T helper 2 (Th2) subsets of CD4+ T helper cells, which is therefore worthy of exploration. Selective control of immune response by the two T helper subsets is by release of different cytokines that promote either cellular or humoral immunity, the latter of which may be associated with inappropriate immune responses and with immune dysfunction. Discovery of the Th1 and Th2 subsets and definition of the cytokines they release provide a new avenue toward possible development of a safe and effective vaccine and an approach, in addition, to correction of immune dysfunction by selective cytokine administration or by cytokine ablation by antagonists or antibodies. AIDS pathogenesis and immune dysfunction are complex and understanding them may be overwhelmed by an excess of possibilities. Simplification of the endeavor might benefit from comparative studies of the pathogenesis of measles, in which there also is immune deficiency but usually with spontaneous viral clearance, reversal of immune dysfunction, and total recovery. In addition, measles presents as a single disease and is caused by antigenically stable virus. Identification of the process whereby measles immunodeficiency is spontaneously reversed might be of importance in attempting to devise means for similar reversal in AIDS.