Affinity-matured B cell responses neutralizing type-I interferons underlie severe viral infections
Summary
Autoantibodies neutralizing type-I interferons (AAN-I-IFNs) emerge as global, common, and strong determinants of a growing number of severe viral diseases. We report that AAN-I-IFNs+ patients with life-threatening COVID-19 pneumonia harbor circulating type-I IFN-specific B cells indistinguishable from patients bearing T cell tolerance defects of genetic origin. This autoimmune response mobilizes a highly diverse and stable circulating B cell response that is detected prior to severe viral
Content
# Affinity-matured B cell responses neutralizing type-I interferons underlie severe viral infections
*Published: 2026 May 6*
Autoantibodies neutralizing type-I interferons (AAN-I-IFNs) emerge as global,
common, and strong determinants of a growing number of severe viral diseases. We
report that AAN-I-IFNs+ patients with life-threatening COVID-19 pneumonia harbor
circulating type-I IFN-specific B cells indistinguishable from patients bearing
T cell tolerance defects of genetic origin. This autoimmune response mobilizes a
highly diverse and stable circulating B cell response that is detected prior to
severe viral infection and acquires high affinity and neutralization potential
to type-I IFNs through extended somatic hypermutation. X-ray crystallography and
AlphaFold3 structural analysis of hundreds of patient-derived monoclonal
antibodies reveals the extended breadth of this response, targeting three major
B cell epitopes covering all facets of type-I IFNs. These findings support a
model in which a germinal-center-derived memory B cell response directed against
type-I IFNs is established before severe viral infection, providing a core
mechanism linking T cell tolerance defect to pathogenic AAN-I-IFNs underlying
severe viral diseases.
DOI: 10.1016/j.cell.2026.04.013