Figure 5. CD122 phenotype and function on rhesus macaque CD8 T cells.

(A) Rhesus PBMCs were analyzed by FACS. Gates based on lymphocytes were defined by forward and side-scatter, (B) further gated on CD3⁺ T cells and then (C) CD8⁺ T cells and CD4⁺ T cells. (D) Gating on CD8⁺ T cells, an isotype control was utilized to define (E) CD122^– versus CD122⁺ CD8⁺ T cells. (F) CD122^– cells demonstrated higher frequencies of CD28⁺CD95^– naive CD8⁺ T cells in contrast to (G) CD122+ cells which were predominantly T_EM CD28^–CD95⁺ or T_CM CD28⁺CD95⁺ CD8⁺ T cells. (H–J) The increased memory phenotype of CD122⁺ (gray bars) CD8⁺ T cells versus the more naive phenotype of CD122^– (black bars) CD8⁺ T cells is depicted graphically. (K) The addition of IL-15 in vitro increased frequencies of CD8⁺ T cells recruited into the effector response as measured by dual IFN-γ and TNF production. IL-15 augments effector function across the spectrum of memory differentiation, as defined by CD28, CD95, CD45RA, and CCR7 expression. (L) IL-15 was superior to IL-2 in recruiting CD8⁺ T cells into an effector response. IL-15 augments cytokine production by CD28⁺CD95⁺ cells compared with CD28^–CD95⁺ cells (P < 0.0001). (H–J) P values were generated by Student’s t test, 2-tailed. (L) P values were generated by 1-way ANOVA followed by Tukey’s multiple comparisons test; bars represent the mean ± SEM of 3–6 rhesus macaques. Results are representative of 3 independent experiments. *P < 0.05; **P < 0.01; ****P < 0.0001.