IL-2 negatively regulates IL-7 receptor [alpha] chain expression in activated T lymphocytes

Interleukin (IL)-2 is a type I four-[alpha]-helical bundle cytokine that plays vital roles in antigen-mediated proliferation of peripheral blood T cells and also is critical for activation-induced cell death. We now demonstrate that IL-2 potently decreases expression of IL-7 receptor [alpha] chain (IL-7R[alpha]) mRNA and protein. The fact that IL-7R[alpha] is a component of the receptors for both IL-7 and thymic stromal lymphopoietin (TSLP) suggests that IL-2 can negatively regulate signals by each of these cytokines. Previously it was known that the IL-2 and IL-7 receptors shared the common cytokine receptor [gamma] chain, [[gamma].sub.c] which suggested a possible competition between these cytokines for a receptor component. Our findings now suggest a previously unknown type of cross-talk between IL-2 and IL-7 signaling by showing that IL-2 signaling can diminish IL-7R[alpha] expression via a phosphatidylinositol 3-kinase/Akt-dependent mechanism.