Flow cytometry analysis (Supplemental Figure 2) of lung single-cell suspensions on day 60 after influenza infection revealed an increased percentage of alveolar epithelial type 2 (AT2) cells (CD45–T1α–CD31–EpCAM+/CD326+MHCII+) and endothelial cells (CD45–T1α–EpCAM–/CD326–CD31+) (Figure 2, A and B, and Figure 2, D and E, respectively) compared with the naive state. This evidence concerns the gene PECAM1 and influenza.