The number of CD8+ cells per square millimeter was higher in early than in end-stage IPF [93 (16–184) cells/mm2 vs. 44 (7.6–196) cells/mm2; p = 0.006] and smoking controls [63 (5.4–161) cells/mm2; p = 0.03; Table 2, Supplementary Figure S2]. This evidence concerns the gene CD8A and idiopathic interstitial pneumonia.