Mice that received M1/MDIVI1–treated Tregs had significantly better lung function compared with mice with cGVHD (Figure 10, A–C), with overall similar pulmonary function to the BM-only control group (Supplemental Figure 8H), as well as reduced lung fibrosis (Figure 10, D and E), fewer GC B cells and Tfh cells (Figure 10, F and G), and an increase in the overall Tfr cell frequency as well as the Tfr/Tfh cell ratio (Figure 10, H and I). Here, TFRC is linked to pulmonary fibrosis.