The cytokine composition of plasma from patients with HLH confers DEX resistance in CD8 T cells. (A) Levels of common γ-chain cytokines in plasma from control patients versus patients with HLH. (B) Viability relative to vehicle control of human CD8 T cells following exposure to 1 µM DEX for 48 hours in the presence or absence of 10 ng/mL of the indicated cytokine in technical triplicate. Statistical significance is relative to the vehicle condition. (C) MFI and representative histograms of pSTAT5 in human CD8 T cells following stimulation with 100 ng/mL of the indicated cytokine for 15 minutes in technical triplicate. Statistical significance is relative to the basal condition. (D) Viability relative to vehicle control in human CD8 T cells cultured in plasma from control patients or patients with HLH and treated with 1 µM DEX for 48 hours. Statistical significance was assessed using 2-sample Student t tests (A and D) or 1-way ANOVA with Tukey’s method for multiple comparisons adjustment (B and C). The data in panels B and C are representative of 3 independent experiments. ****P < .0001; ***P < .001; **P < .01; *P < .05.