Objective: Antinuclear antibodies (ANA) are detected in approximately a quarter of COVID-19 patients when assessed by indirect immunofluorescence. Since there is no information, our study investigated the presence of ANA detected by Enzyme-Linked Immunosorbent Assay (ELISA) and its clinical and laboratory associations.
Patients and methods: A longitudinal study was conducted on 92 patients with severe COVID-19, 20 patients with acute myocardial infarction, and 25 healthy subjects. Blood samples were obtained at hospital admission. Commercial ELISA was used to detect ANA, while flow cytometry was used to measure serum interferons.
Results: ANAs were positive in 8.6% of COVID-19 patients, 10% of myocardial infarction patients, and 4% in healthy individuals (p=0.676). COVID-19 patients with ANA+ had less ferritin, troponin, and neutrophils but more albumin and lymphocytes than ANA- patients. Serum levels of type I, II, and III interferons were similar between groups. At follow-up, all ANA+ patients survived, while mortality was significant in ANA- patients (0 vs. 36%; p=0.048).
Conclusions: ANA detection is not increased in severe cases of COVID-19 when assessed by ELISA. However, its presence appears to be associated with a less aggressive disease phenotype, regardless of circulating levels of interferons.