PTPRC and susceptibility to pneumonia measurement: Based on this finding along with prior evidence that LOX-1 on macrophages can contribute to vascular injury (13), we assessed LOX-1 surface expression on intra- and extravascular monocytes (CD45+F4/80–CD11b+Ly6C+), interstitial (nonalveolar) macrophages (CD45+F4/80+CD11b+SiglecF–Ly6C–), and alveolar macrophages (CD45+F4/80+SiglecF+) collected from collagenase-digested lungs following 24 hours of pneumonia (Figure 4B).