Decreased survival of CCR7 KO memory cells in IL-15 KO mice, but not in IL-7 KO mice. (A) P14 CCR7 WT or KO memory cells were formed in WT (open bar) and IL-15 KO (closed bar) mice and analyzed on day 35 pi. (B) P14 CCR7 WT or KO memory cells were formed in WT (open bar) and IL-7 KO (closed bar) mice and analyzed on day 35 pi. Bar graphs show the mean ± SEM ratios of P14 CCR7 WT and KO cells in the spleen, liver, lung, LN, and BM. Data are representative of three similar experiments. *P < 0.05.