Figure 6.

COVID-19 disease induces a small but significant infiltration of CD3 lymphocytes into the lung. Staining for nuclei (DAPI, blue staining), SARS-CoV-2 protein M (SARS-CoV-2-M, green staining), CD3 lymphocytes (CD3, red staining), and SARS-CoV-2-mRNA (White staining) was performed. 3D reconstructions of lung samples collected from uninfected (control) and COVID-19 (Type 1 or 2, enhanced coagulation, and immune infiltration). In control conditions, lymphocytes were mostly randomly attached to the alveolar wall (Control). In contrast, in the enhanced coagulation phenotype (COVID-19, type I, damage), a significant infiltration of lymphocytes was observed (COVID-19-type 1), but most of this infiltration was localized, and most areas were negative for CD3⁺ cells. No CD3⁺ lymphocytes were positive for viral mRNA or the viral protein M. As indicated in the previous figure, most viral protein M staining was concentrated inside blood vessels (see yellow arrows). In the immune infiltrating phenotype, we observed a significant increase in lymphocyte infiltration, but as indicated above, infiltration was region-specific, and most areas were negative for CD3 staining. (n = 13-15 different cases analyzed with a least five sections each).