PDCD1 and lung cancer: Median PD-1% expression was significantly higher in lymphocytes derived from mediastinal lymph nodes of patients with IPF compared to lung cancer (IPF: 2.0, 95% CI: 0.5 to 3.0 vs. lung cancer: 0.0, 95% CI: 0.0 to 0.8, p = 0.02), (Fig. 3, Panel A).