Figure 5. The kinase activity of ITK is required for Tr1 cell suppressive function.

Differentiated and sort purified WT and Itk_as Tr1 cells (CD45.2⁺, carrying IL-10^GFP/Foxp3^RFP reporters) were co-cultured with CFSE stained naive CD4⁺ T cell responders (CD45.1⁺). 3MBPP1 was added to specifically inhibit ITK_as activity. (a) Representative FACS plots of WT and Itk_as Tr1 cells and CFSE dilution of the CD45.1⁺ responders with or without stimulation in the presence or absence of ITK-inhibited Tr1 cells or control cells (responder cell density was fixed and Tr1 cells were added at the indicated ratios). (b) Summary of percentage of suppression of the responder proliferation by the ITK-inhibited Tr1 cells or control cells. P value calculated by two-way ANOVA. (c) Relative (Rel) IL-10 MFI in CD45.2⁺ Tr1 cells in the co-culture system. WT average level was set as 1. *P≤0.05, **P≤0.01, ***P≤0.001, by non-parametric Mann–Whitney test. n=6. Data represents results of three experiments. Data presented as mean±s.e.m.