IL-15 induces CD4⁺ effector memory T cell production and tissue emigration in nonhuman primates
J. Clin. Invest. Louis J. Picker, et al. 116:1514 doi:10.1172/JCI27564 [Go to this article.]

Figure 3
CD28^– , CCR7^– T_EM cells are poorly responsive to IL-2. (A) The CD4⁺ and CD8⁺ memory T cell subsets defined by CD28 and CCR7 expression in the peripheral blood in 2 representative RMs (of 4 total) were assessed for expression of Ki-67 before, during, and after 2 weeks of twice-weekly administration of IL-2. Note that IL-2 preferentially induced proliferation in the CD28⁺CCR7^– component of both the CD4⁺ and the CD8⁺ memory populations. (B) The mean (± SEM) change in percentage Ki-67 from baseline (the average of day –7 and day 0 values) to peak response (day 7 or 10 after the first cytokine dose) is shown for the CD28/CCR7–defined peripheral blood memory T cell subsets in all 4 IL-2–treated RMs, and the 4 RMs that received at least 3 doses of IL-15 (the pre-peak doses on days 0, 3, and 7, matching the pre-peak IL-2 dosing schedule). While IL-2 demonstrated a superior (to CD4⁺) or similar (to CD8⁺) ability to induce proliferation among CD28⁺CCR7^– transitional memory T cells, IL-15 was dramatically better than IL-2 in initiating proliferation within both the CD4⁺ and the CD8⁺, CD28^–CCR7^– T_EM subsets. *0.05 < P < 0.005; **P < 0.005.