Antinuclear antibodies (ANAs) detected by indirect immunofluorescence (IIF) method in acute COVID-19 infection; future roadmap for laboratory diagnosis

As in other viral infections, anti-nuclear antibodies (ANAs) are observed in SARS-CoV-2 infection. We investigated the presence of autoantibodies in acute COVID-19 and the association with early laboratory findings. We examined 50 sera (>18 years, 25 Female) from patients with acute COVID-19. ANAs (HEp-20-10 liver biochip), anti-neutrophil cytoplasmic antibody (ANCA, Europlus Granulocyte Mosaic 32) and anti-double stranded DNA were investigated with product of Euroimmune AG (Luebeck, Germany) by indirect immunofluorescence (IIF) method. Also, antibody against cyclic citrullinated peptide (anti-CCP) was examined by a chemiluminisens assay (Euroimmun AG, Luebeck, Germany). Samples from 50 blood bank donors collected before the COVID-19 pandemic were used as controls. The IIF-ANA test was positive in 18% (N = 9/50) of the patients. The median time of sample collection was 7 days (range: 1–28 days) after diagnosis. ANA was positive in only one (2%) control sample. Five (55.5%) patients were ANA positive with a strong titer (3+). There was no relationship between antibody titration and time of sample collection (p = 0,55). Anti-CCP was detected in a nucleolar (3+) positive patient (2%). ANA was detected in 14.28% (N = 1/7, rods-rings (±), p = 0,78) of patients in the intensive care unit(ICU). Patients treated in the clinic have more and higher titers of ANA, mostly in nucleolar patterns, than ICU patients. The variety of antibodies detected in acute COVID-19 and the uncertainty of how long they persist can lead to confusion, especially in the diagnosis of systemic autoimmune rheumatic diseases for IIF-ANA testing in immunology laboratories. Improvements in cell lines and methods will facilitate the diagnostic process. •ANAs were in higher titers and mainly in nucleolar patterns in acute COVID-19 in the IIF assay.•ANAs could be observed together with vasculitis-associated antibodies and/or extractable ANA patterns in acute COVID-19.•ANA titers were higher in patients monitored in the clinic than in the intensive care unit.•The variability and uncertainty in antibody response in COVID-19 may pose a challenge in diagnosing SARD for IIF testing.