MKI67 and idiopathic pulmonary fibrosis: Compared with HCs, IPF patients displayed a slight increase in the percentages of Ki-67+ cells in rTreg (0.72 ± 0.34% vs 3.98 ± 2.44%, p = 0.004; Fig. 2c) but a more dramatic increase in aTreg subsets (4.54 ± 2.86% vs 35.20 ± 12.07%, p < 0.001; Fig. 2d), which indicates that aTregs in IPF patients are hyper-proliferative.