Figure 2.

(A) Detection of complement components in lung sections by immunofluorescence analysis. The panel shows representative immunofluorescence images obtained from the analysis of several sections of lung autopsy samples from 12 SARS-CoV-2-positive and 3 negative cases. The sections were stained to reveal the presence of C4, C3, and C5b-9, as explained in materials and methods, and examined by three independent observers. Scale bar = 50 µm. (B) Evaluation of complement components by western blot in the lungs of a COVID+ and a COVID− patients. The columns represent the staining intensity of the western blot bands quantified using ImageJ (Fuji-NIH). Western blot bands of C4 and C3 are shown on top of the corresponding columns. C5b-9 levels were measured by ELISA and expressed as OD readings at 405 nm.