Regulation of mature T cell homeostasis.

The overall size and the composition of the mature T cell pool are regulated by homeostatic mechanisms. Recent work has revealed that homeostatic signals are received from contact with two members of the common gamma chain family of cytokines, IL-7 and IL-15, and from self-MHC/peptide ligands. In essence, homeostasis of naïve T cells is regulated by IL-7 and self-MHC/peptide ligands and homeostasis of memory CD8 cells is controlled by IL-7 and IL-15. All of these signals also appear to be important to a varying degree for homeostasis of memory CD4 cells, but the details are less well understood than for other cell type.