ABSTRACT
Interleukin-2 (IL-2) is the principal regulatory signal that controls the proliferation and differentiation of cells which can exhibit cytotoxic activity against a variety of target cells. IL-2 was originally defined as a growth signal for the development of antigen-specific cytolytic T lymphocytes. The IL-2 receptor was first described in T lymphocytes by experiments in which the IL-2 activity contained in crude supematants was absorbed out by activated T cells. The regulation of the effector kinase by PK-C or other kinases provide evidence for the existence of interkinase modulations propagating the initial membrane kinase activation and controlling the vast number of biochemical reactions required for the maintenance of cell viability and gene expression. Since both phorbol ester and IL-2 stimulate the phosphorylation of overlapping, but distinct, sets of proteins, it can be inferred that both protein kinase C and at least one, though probably more than one, additional kinase activity are stimulated by IL-2.
