FIGURE 4. The p105 deficiency does not inhibit the development and effector function of Tregs but renders CD4 effector T cells insensitive to Treg-mediated suppression.

A, Thymocytes, splenocytes, and mLN cells were subjected to flow cytometry, and the frequency of CD4⁺CD25⁺FoxP⁺ Tregs were presented as percentage of total CD4 T cells. B, WT effector CD4 T cells were activated in the presence of the indicated ratios of either WT or p105^−/− Tregs, and the proliferation of effector T cells was analyzed based on ³H-thymidine incorportation. The level of Treg suppression was calculated as percentage of suppression based on the proliferation of effector T cells in the absence of Tregs. C, WT and p105^−/− naïve CD4 T cells were stimulated either in the absence or presence of the indicated ratios of WT Tregs, and the proliferation of the effector CD4 T cells was analyzed based on ³H-tritium incorporation. Suppression was calculated as described in in B.