IgA is the predominant isotype of anti-β2 glycoprotein I in patients with COVID-19.

Abstract

The aim of this research was to determine the frequency of antiphospholipid antibodies (aPL) in patients with COVID-19. The frequency and titers of anticardiolipin antibodies (aCL) and anti-β2 glycoprotein I antibodies (aβ2GPI) were determined in sera of adult patients hospitalized with COVID-19. Immunoglobulin (Ig)G, IgA, IgM aCL, and aβ2GPI were measured using enzyme-linked immunosorbent assay. Eighty-three patients were included in the study. The mean age of patients was 62 ± 13.9 years, ranging from 23 to 86 years. Stratification according to severity of infection divided patients in 2 groups: 45 patients with moderate infection and 38 patients with critical or severe infection. Out of the 83 patients suffering from COVID-19, aPL (aCL or aβ2GPI) were detected in 24 patients (28.9%). IgG, IgA and IgM aβ2GPI were positive in 2.4%, 16.9% and 8.4%, respectively. IgG, IgA and IgM aCL showed positivity in 7.2%, 0%, and 4.8%, respectively. The frequency of aPL was 36.8% in patients with critical/severe infection and 22.2% in patients with moderate infection. In critical/severe patients, the frequency of aβ2GPI was significantly higher than aCL (34.2% vs 13.2%, P = .03) and aβ2GPI-IgA were significantly more frequent than aβ2GPI-IgG (21.1% vs 2.6%, P = .028). In this cross-sectional study, aPL and particularly aβ2GPI-IgA were common in patients with COVID-19.