Disease severity (Acute Physiology and Chronic Health Evaluation [APACHE] II [A], Sequential Organ Failure Assessment [SOFA] [B], and Multiple Organ Dysfunction Syndrome [MODS] [C]), duration of mechanical ventilation (D), and length of stay (LOS) in intensive care unit (ICU) (E) in patients with different programmed death receptor 1 ligand 1 (PD-L1) levels on neutrophils. *P < 0.05 by Mann–Whitney U test.