Endogenous proliferation: burst-like CD4 T cell proliferation in lymphopenic settings.

Rapid and slow proliferation is observed when naïve CD4 T cells are transferred into lymphopenic hosts. We have recently proposed that the rapid, burst-like proliferation, designated endogenous proliferation, is a peripheral mechanism by which memory T cells of diverse specificity are generated without exogenous antigenic stimulation. In this review, we discuss some of unique features of endogenous proliferation. We argue that it is regulated not by the absolute number of memory cells present but by the range of specificities of those cells. We discuss the physiologic significance of endogenous proliferation and outline goals for future studies.