Interleukin 4/B cell stimulatory factor 1: one lymphokine, many functions.

Lymphokines are multifunctional T cell products that profoundly regulate the activation, growth, and differentiation of many cell types, most notably T cells and B cells. One of the lymphokines with the broadest range of actions is interleukin 4/B cell stimulatory factor 1. The characteristics, function, and regulation of interleukin 4 are reviewed as part of an overall discussion of the mechanism through which T cell-derived lymphokines control immune responses in vivo and in vitro.