CD8(+) T-cell homeostasis after infection: setting the 'curve'.

Antigen (Ag)-specific CD8(+) T-cell responses exhibit remarkably similar kinetics after different types of infection. Starting from levels that are virtually undetectable in vivo, pathogen-specific naïve CD8(+) T cells are precisely regulated to go through rapid expansion and contraction (death) phases, achieving memory levels of Ag-specific CD8(+) T cells that are maintained for the life of the host. However, the exact mechanisms used to achieve appropriate and reproducible CD8(+) T-cell homeostasis in response to diverse pathogens remain to be determined. The possibility that early events after infection regulate major features of Ag-specific CD8(+) T-cell homeostasis will be discussed here.