PDCD1 and colitis: The results showed that percentages of CD4+CXCR5+PD-1+ Tfh and Tfh/Tfr ratios in the MLNs and spleen of colitis mice increased significantly compared to those of normal mice (p < 0.05), while no statistical difference was found in CD4+CXCR5+Foxp3+ Tfr (p > 0.05) (Figure 11).