Decreased production of Th2 cytokines by viperin-deficient CD4⁺ T cells. (A) IL-2 production from CD4⁺ T cells after stimulation with anti-CD3 with or without anti-CD28 Abs for 24 hours. (B) BrdU incoporation assay for T cells primed with a serial concentration of anti-CD3 mAb or in conjunction with anti-CD28 (5 μg/mL). (C) Th1 and Th2 cytokine production in supernatants were analyzed after stimulation for 72 hours. The data shown are representative of more than 10 independent experiments, each using different mice. ND indicates not detectable. (D) Amount of IFN-γ and IL-4 was measured in culture supernatants of CD4⁺ T cells following stimulation with 5 ng/mL PMA plus 500 ng/mL ionomycin for 4 days. IL-5 and IL-13 production was determined after a 5-day culture. A representative of 5 independent experiments is shown. *P < .05; **P < .01, WT versus knockout (KO). (E) RNA expression of cytokines in stimulated T cells was analyzed by real-time RT-PCR. A representative of 3 independent experiments is shown. All data are expressed as the mean value of duplicate-triplicate determinations plus or minus SD. *P < .05; **P < .01 WT versus KO at most of the time points for IL-4, IL-5, and IL-13 determined by Student t test.