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. 2021 May 17;9(5):e002024. doi: 10.1136/jitc-2020-002024

Figure 2.

Figure 2

The rhIL-15 and NKTR-255 have different signaling and leukocyte degranulation properties in vitro compared with precomplexed rhIL-15/IL-15Rα cytokines. (A) Dose-response curves for pSTAT5, pAKT and pERK in NK, CD8+ T and CD4+ T cells following stimulation with rhIL-15, NKTR-255, rhIL-15/IL-15Rα or rhIL-15 N72D/IL-15Rα in human whole blood (n=6). (B) pSTAT5 EC50 ratios for CD8+ T/NK cells and CD4+ T/NK cells and (C) EC50 ratios for pAKT/pSTAT5 or pERK/pSTAT5 in NK cells (*p<0.05, **p<0.01; Dunnett’s multiple comparisons test vs rhIL-15). Human peripheral blood mononuclear cells (n=3) were stimulated in vitro with rhIL-15, NKTR-255, rhIL-15/IL-15Rα and rhIL-15 N72D/L-15Rα Fc overnight to assess (D) CD107a surface expression by flow cytometry (n=3) and (E) secreted granzyme B by Meso Scale Discovery (n=3; *p≤0.05, **p≤0.01, ***p≤0.001, ****p≤0.0001; Dunnett’s multiple comparisons test vs vehicle). EC50, half maximal effective concentration; IL, interleukin; IL-15Rα, IL-15 receptor α; NK, natural killer; pAKT, phosphorylated AKT; pERK, phosphorylated ERK; pSTAT5, STAT5 phosphorylation; rhIL-15, recombinant human IL-15; STAT5, signal transducer and activator of transcription.