Control of homeostasis of CD8+ memory T cells by opposing cytokines

Memory T cells maintain their numbers for long periods after antigen exposure, Here we show that CD8(+) T cells of memory phenotype divide slowly in animals. This division requires interleukin-15 and is markedly increased by inhibition of interleukin-2 (IL-2), Therefore, the numbers of CD8(+) memory T cells in animals are controlled by a balance between IL-15 and IL-2.