Figure 5. Neutrophil influx, and NETosis in the lung parenchyma of COVID-19 lung autopsy cases.
(A) H&E staining of lung tissues with massive neutrophil influx. (B) Neutrophils show high expression of neutrophil elastase. (C) Insert from panel B depicts extracellular release of NE (white asterisk) in the alveoli. (D) Lung sections with immunohistochemistry for MPO also indicate neutrophil activation. (E) PAD4 staining. (F) Increased levels of total citrullinated proteins in the lungs of COVID-19 patients compared to COVID-19-negative patients. Scale Bar=100 μm.