B7-H1 expression is associated with expansion of regulatory T cells in colorectal carcinoma

Figure 4 PD-1 expression on CD4⁺Foxp3⁺ or CD8⁺Foxp3⁺ regulatory T cells and conventional T cells in colorectal carcinoma tissues. Mononuclear cells were harvested from fresh tumor tissues of the same colorectal carcinoma patient. The PD-1 expression was determined by fluorescence-activated cell sorting analysis, gated on CD4⁺Foxp3^+/- or CD8⁺Foxp3^+/- T cells. A: CD4⁺Foxp3⁺ regulatory T cells could hardly express PD-1 on the cell surface, while PD-1 expression level was significantly higher on the conventional CD4⁺T cells; B: CD8⁺Foxp3⁺ regulatory T cells almost failed to express PD-1, while PD-1 expression was significantly higher on the conventional CD8⁺T cells as well.