IL-15 treatment does not lead to long-lasting (day 48) accumulation of NK and memory T cells, but chronically alters the balance of CD4⁺and CD8⁺T cells. (A) Frequency of total T (CD3⁺) cells and NK (either CD56⁺ or CD16⁺) cells relative to the frequency of B (CD20⁺) cells in the lymphocyte gate and (B) percentage of CD56⁺CD16⁻ NK cells, CD56⁻CD16⁺ NK cells, and CD95⁺ memory CD4⁺ and CD8⁺ T cells as found in different tissues at day 48 after treatment with IL-15. (C) Top, representative example of the percentage of the CD4⁺ and CD8⁺ cells inside the CD3⁺ gate in the MLN, ALN, and ILN at the same time point. Bottom, CD4:CD8 ratio as found in different tissues and in the PBMCs at day 48 after treatment with IL-15. Data in panels A through C were expressed as in Figure 3B. *P < .05 after Wilcoxon rank test versus sham.