VOLUME 13 NUMBER 2 (July to December 2020)

Ivan Christian VJ. Imperial, Giann Kerwin Y. Dellosa, and Joyce A. Ibana*

¹Immunopharmacology Research Laboratory,
      Institute of Biology, College of Science,
      University of the Philippines, Diliman,
      Quezon City, 1101 Philippines

Despite the nature of COVID-19 as a disease of mucosal tissue sites, current serological tests are primarily focused on IgM and IgG antibody detection. The significance of testing for IgA antibody response to SARS-CoV-2 infection and their potential role in COVID-19 disease progression is not yet well explored. Intriguingly, several studies revealed that heightened IgA antibody response to SARS-CoV-2 correlated with COVID-19 disease severity. We hypothesize that the assessment of serum IgA levels can aid in the prognostication of severe COVID-19 progressors. Our hypothesis posits that an IgA antibody response to SARS-COV-2 that is skewed towards Fc binding to CD89 (FcαRI) to form immune complexes (IgA-IC) rather than inhibiting viral entry to host epithelial cells, results in IgA-IC-mediated hyperinflammatory response. The propensity for an elevated non-neutralizing IgA antibody response in sera of COVID-19 patients may lead to the unregulated crosstalk between PRR-induced priming of inflammation and IgA-IC-induced NLRP3 inflammasome formation. Therefore, we believe that looking into the dynamics of the SARS-CoV-2-specific IgA response and their threshold values associated with the clinical severity of COVID-19 warrants further investigations. If our hypothesis is correct, serum IgA may supplement, if not precede, traditional serum diagnostic markers of end-organ damage that are currently used for COVID-19. Investigating the feasibility of using IgA as a biomarker for severe COVID-19 progressors in future studies may reveal its underappreciated value in improving current clinical management and treatment of SARS-CoV-2 positive patients.