Sequential and parallel regulation of immune system reactivity

The essential feature of the immune system (IS) is the recognition of antigens (Ags), both self and nonself. The key stage of the IS function is that in which its functional way is oriented toward either the helper or the suppressor line. The regulation of this helper-suppressor assembly is obtained by complex mechanisms, which have led to two working hypotheses in the attempt to explain many immune phenomena (self-tolerance, defense of organism, and destruction of nonself). These theories are: a. the clonal balance theory, or the theory of functional ratio between helper and suppressor clones, and b. the sequential theory, or the theory of immune network between idiotypes and antiidiotypes.