NFKB2 haploinsufficiency identified via screening for IFNα2 autoantibodies in children and adolescents hospitalized with SARS-CoV-2-related complications

Abstract

Background Autoantibodies against type I interferons (IFNs) occur in approximately 10% of adults with life-threatening COVID-19. The frequency of anti-IFN autoantibodies in children with severe sequelae of SARS-CoV-2 infection is unknown. Objective To quantify anti-Type I IFN autoantibodies in a multi-center cohort of children with severe COVID-19, Multisystem Inflammatory Syndrome in Children (MIS-C), and mild SARS-CoV-2 infections. Methods Circulating anti-IFNa2 antibodies were measured by a radioligand binding assay. Whole exome sequencing (WES), RNA-sequencing, and functional studies of peripheral blood mononuclear cells were used to study any patients with levels of anti-IFNα2 autoantibodies exceeding the assay’s positive control. Results Among 168 patients with severe COVID-19, 199 with MIS-C, and 45 with mild SARS-CoV-2 infections, only one had high levels of anti-IFNα2 antibodies. Anti-IFNα2 autoantibodies were not detected in patients treated with intravenous immunoglobulin prior to sample collection. WES identified a missense variant in the ankyrin domain of NFKB2, encoding the p100 subunit of NF-kB essential for non-canonical NF-kB signaling. Her peripheral blood mononuclear cells exhibited impaired cleavage of p100 characteristic of NFKB2 haploinsufficiency, an inborn error of immunity with a high prevalence of autoimmunity. Conclusions High levels of anti-IFNα2 autoantibodies in children and adolescents with MIS-C, severe COVID-19, and mild SARS-CoV-2 infections are rare, but can occur in patients with inborn errors of immunity. Clinical implications Anti-IFNα2 autoantibodies should prompt diagnostic evaluation for inborn errors of immunity if identified in children or adolescents.