CD274 expression was not detected in AT2s, but a small HTII-280neg CD274pos population (called CD274pos; from here on, population Q3) was present in the donor and was statistically increased in the lungs of IPF patients (Figure 2A,B, Figure S3D, population Q3 donor vs. IPF = 0.54% ± 0.255% vs. 10.48% ± 10.32%, respectively, p < 0.001). Here, CD274 is linked to idiopathic pulmonary fibrosis.