Regulation of antigen-specific CD8(+) T cell homeostasis by perforin and interferon-gamma

T cell memory depends on factors that regulate expansion and death of these cells after antigenic stimulation. Mice deficient in perforin and interfer on-gamma (IFN-gamma) exhibited increased expansion, altered immunodominance , and decreased death of antigen-specific CD8(+) T cells after infection wi th an attenuated strain of Listeria monocytogenes, which was cleared from t hese mice. Expansion of CD8(+) T cells was controlled by perforin, whereas IFN-gamma regulated immunodominance and the death phase. Thus, perforin and IFN-gamma regulate distinct elements of CD8(+) T cell homeostasis independ ently of their role as antimicrobial effector molecules.