Fig. 4. GITR deficiency in Rag^−/− recipients caused an over expansion of naïve T cells as well as a loss of FoxP3 expression on Treg cells.

CD4⁺CD45RB^hi naïve T cells sorted from Thy1.1⁺ B6 congenic mice were mixed with CD4⁺FoxP3⁺ Treg cells from Thy1.2⁺ FoxP3-IRES-GFP reporter mice at 9:1 ratio and adoptively transferred to GITR^−/−xRag^−/− or Rag^−/− hosts (5 mice for each group). Mice were weighed weekly and euthanized for colitis activity as described in Figure 1. Spleen, MLN and lamina propria cells from GITR^−/−xRag^−/− or Rag^−/− recipients were isolated and evaluated for FoxP3⁺, Thy1.1⁺ and Thy1.2⁺ cells.

4A Weight loss as a percentage of the initial weight. Values represent the mean weight ± SD.

4B DAI. Mean and individual values of each group are indicated.

4C Ratio of Thy1.1⁺ and Thy1.2⁺ cells after cell transfer. Thy1.1⁺ cells represent CD4⁺CD45RB^hi naïve T cells. Thy1.2⁺ cells represent FoxP3⁺(GFP⁺) cells.

4D Percentage of FoxP3(GFP)⁺/Thy1.2⁺ cells after cell transfer.

4E Percentage of FoxP3⁺ cells expressing Thy1.1⁺ and Thy1.2⁺. Splenocytes from GITR^−/−xRag^−/− or Rag^−/− recipients were stained with CD4, Thy1.1 and FoxP3. Thy1.1 and FoxP3 expressing cells were compared among gated CD4⁺ T cells.