When circulating CD45+collagen-1+ fibrocytes were compared between disease groups, an increased proportion was found in both BO patients (p < 0.001) and PF (p < 0.05) patients, when compared to Donors (Median BO = 7.02%, Median PF = 2.07%, Median Donors = 0.85%) (Figure 2C). Here, PTPRC is linked to bronchiolitis obliterans syndrome.