Maintenance of effector-memory Maxi CD8 T cells is dependent on IL-15 but independent of IL-7 or IL-2.

(A) Naïve Maxi CD8 T cells were adoptively transferred into naïve C57BL/6 mice followed by i. v. MCMVΔm157 infection. Effector-memory Maxi T cells were sorted from the lungs and transferred into C57BL/6 recipients or knockout recipients. Recipients were administered i.p. during 30 days with receptor-blocking or cytokine neutralising antibodies every second day. Total numbers of Maxi cells were assessed in the lungs at 4 weeks post transfer. (B) Percentage of recovered Maxi cells normalized to untreated control is shown as mean + SEM of n = 4–12 mice pooled from five independent experiments. (C) Representative Bcl-2 histogram gated on Maxi CD8 T cells. (D) Mean fluorescence intensities of Maxi CD8 T cells are shown as mean + SEM of n = 4 mice representative of two independent experiments. (E) Mean fluorescence intensities of pSTAT5 in inflationary Maxi cells are shown as mean + SEM of n = 6 mice pooled from two independent experiments. (F) Representative Bcl-2 histogram gated on Maxi CD8 T cells and mean fluorescence intensities of Bcl-2 in inflationary Maxi cells are shown as mean + SEM of n = 6 mice pooled from two independent experiments. (B, D-F) *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001. Statistical analyses were performed using the non-parametric Mann-Whitney U test.