Figure 5.

Patients with COVID-19 have antibodies that recognize neutrophils and NET’s antigens. (A) Healthy donor neutrophils were seeded on coverslips and stimulated with 2.5 mM PMA to induce the release of NETs. The samples were incubated with 10% sera from COVID-19 patients or healthy donors. Sera from COVID-19 patients show anti-neutrophil and anti-NET antibodies. The antigens recognized by anti-neutrophils and anti-NET antibodies include those located in the cytoplasm (continuous arrow), nucleus (arrowhead) and NETs (discontinuous arrow). The autoantibodies were not found in healthy donors. As the isotype control, the samples were incubated solely with the secondary antibody. (B) Relative amount of anti-NET antibodies expressed as the optic density index (ODI). (C) Titers of antinuclear antibodies expressed in a logarithmic scale. (D) Titers of anti-neutrophil cytoplasmic antibodies. Medians were compared using the Kruskal–Wallis and Dunn’s multiple comparison tests.