IL-21 Induces Apoptosis of Antigen-Specific CD8+ T Lymphocytes

Abstract

IL-21, a member of the common γ-chain family of cytokines, has pleiotropic effects on T, B, and NK cells. We found that IL-21 and the prototype common γ-chain cytokine IL-2 can stimulate proliferation and cytokine secretion by Ag-specific rhesus monkey CD8+ T cells. However, unique among the members of this family of cytokines, we found that IL-21 drives these cells to apoptosis by down-regulation of Bcl-2. These findings suggest that IL-21 may play an important role in the contraction of CD8+ T cell responses.