IgA potentiates NETosis in response to viral infection

IgA is the second most abundant antibody present in circulation and is enriched at mucosal surfaces. As such, IgA plays a key role in protection against a variety of mucosal pathogens including viruses. In addition to neutralizing viruses directly, IgA can also stimulate Fcdependent effector functions via engagement of Fc alpha receptors (Fc-alpha RI) expressed on the surface of certain immune effector cells. Neutrophils are the most abundant leukocyte, express Fc-alpha RI, and are often the first to respond to sites of injury and infection. Here, we describe a function for IgA-virus immune complexes (ICs) during viral infections. We show that IgA-virus ICs potentiate NETosis-the programmed cell-death pathway through which neutrophils release neutrophil extracellular traps (NETs). Mechanistically, IgA-virus ICs potentiated a suicidal NETosis pathway via engagement of Fc-alpha RI on neutrophils through a toll-like receptor-independent, NADPH oxidase complex-dependent pathway. NETs also were capable of trapping and inactivating viruses, consistent with an antiviral function.

Automated summary

IgA plays a key role in protecting against viral infections by potentiating NETosis through neutrophils, which release neutrophil extracellular traps (NETs) to trap and inactivate viruses.