The experimental and clinical use of immune-modulating drugs in the prophylaxis and treatment of infections.

Therapeutic agents capable of stimulating immune responses could be of great value in the prophylaxis and treatment of infectious diseases. Three classes of compounds, each representing a separate approach to the goal of immune stimulation, are discussed with respect to recent experimental and clinical findings. The action of microbial structures and their derivatives can be understood on the basis of "acquired cellular immunity", a phenomenon first described in connection with infections by mycobacteria and other intracellular organisms. In contrast, there is hardly a common denominator for synthetic compounds which are currently used as immune-stimulatory agents. Substances which influence purine metabolism in lymphocytes on the one hand and histamine H2 blockers such as cimetidine on the other hand seem to represent the most promising developments in this field to date. Products of immune cells such as transfer factor and lymphokines form the third and possibly most important group of immune-stimulating agents. Current experimental and clinical trends in this field are briefly described. It is suggested that the delineation of the mechanism of action of lymphokines will open the door to the identification or synthesis of artificial agonists and antagonists as has been the case in the pharmacology of the endocrine and nervous systems.