Role and regulation of interleukin (IL)-2 receptor α and β chains in IL-2-driven B-cell growth

Abstract

Substantial proportions of resting B cells constitutively express low levels of IL-2 receptor (IL-2R) α and/or β chains. The expression of these chains is differentially regulated by anti-IgM and IL-2/IL-4. The anti-IgM induces IL-2R α chain expression, whereas each of the two cytokines induces IL-2R β chain expression in a dose-dependent manner. Moreover, IL-2 induces the growth of B cells, when the cells were pretreated with IL-2 or IL-4 for 24 h. The magnitude of this IL-2-driven B-cell growth depends upon the level of IL-2R β chain expression. Costimulation of the B cells with IL-2 and anti-IgM shifts the dose-response curve, and the cells proliferate at an IL-2 concentration as low as 40 pM. These results indicate that the levels of anti-IgM-induced IL-2R α chain and IL-2-induced IL-2R βchain determine the sensitivity of the cells to IL-2.