Increased cytokine production of 4.1R^−/− T cells. (A,B) Measurements of IL-2 and IFNγ by ELISA. CD4⁺ T cells were stimulated with 5 μg/mL plate-bound anti-CD3ϵ similarly as above. IL-2 (A) and IFNγ (B) in the media were measured with ELISA. The experiments were performed 6 times, and the data shown represent the mean value of triplicate samples from 1 experiment. Error bars indicate SD. (C,D) Intracellular staining of IL-2. The representative profiles of IL-2 expression of 4.1R^+/+ and 4.1R^−/− CD4⁺ T are shown (C), and the quantitative analysis is shown (D). Note a significantly higher percentage of 4.1R^−/− CD4⁺ T cells express IL-2.