Immunologic markers, vasculitis‑associated autoantibodies, and complement levels in patients with COVID‑19

Background: The cause of coronavirus disease 2019 (COVID‑19) is a virus which can lead to severe acute respiratory syndrome‑CoV‑2 (SARS-COV-2). There are evidences of involvement of immune system in pathogenesis of this disease. We investigated the presence of various vasculitis‑associated autoantibodies and complement levels in patients with COVID‑19. Materials and Methods: Patients with severe or critical type of COVID‑19 were evaluated for symptoms, signs, and laboratory tests of vasculitis syndromes including rheumatoid factor (RF), antinuclear antibody (ANA), anti‑double‑stranded DNA, c and p anti-neutrophilic cytoplasmic antibody (c ANCA and P ANCA), and complement levels. Results: The study was performed in forty patients with severe or critical illness. The mean age of the participants was 48.5 ± 9.8 years. All patients had pulmonary involvement in lung computed tomography scans. Vasculitis laboratory test results included RF in two patients, ANA in three patients, and ANCA in one patient. Seventeen (42.5%) patients had hypocomplementemia in one or more complement tests. Four patients expired, of whom three had a decrease in complement level. Conclusion: Decrease in complement levels may predict a critical state of COVID‑19 disease. Therefore, measuring its levels may be of great benefit in making earlier decisions to initiate disease‑suppressing treatments including corticosteroids.