A decrease in the CD31+ fraction of rTreg cells was observed in IPF patients when compared to age-matched HCs (27.79 ± 13.81% vs 45.59 ± 13.44%, p = 0.005; Fig. 2a), suggesting that thymic production of Treg cells was affected in IPF patients and the impaired thymic output contributed to the decrease of rTreg cells. The gene discussed is PECAM1; the disease is idiopathic pulmonary fibrosis.