ABSTRACT
Suppressor factors are soluble inhibitors of the immune response which in have been shown to actively participate in the regulation of the immune system. This chapter focuses on the factors which are produced by lymphoid tissue or those that are present in serum. A nonspecific cytotoxic component termed lymphotoxin was detected in supernatants from in vitro cultures of immune lymphoid cells exposed to specific antigen. Antigen-induced suppression, also referred to as antigenic competition, is a nonspecific immunosuppression in which the administration of an antigen induces a suppression of the immune response to an unrelated antigen. Macrophages are highly mobile cells which actively participate in the induction of the immune response. Prostaglandins can be synthesized by macrophages and also serve as potent immune modulators. Enzymes release by macrophages can be quite extensive. In a few days macrophages can release up to 80% of their content of lysosomes.
