Immunoglobulin A: magic bullet or Trojan horse?

Background Neutrophils participate in the first line of defense by executing several killing mechanisms, including phagocytosis, degranulation and the release of neutrophil extracellular traps. Additionally, they can orchestrate the adaptive immune system by secreting cytokines and chemokines. Opsonization with antibodies aids in the recognition of pathogens, via binding to Fc receptors on the neutrophil surface. Immunoglobulin A (IgA) is the most abundant antibody at mucosal sites and has multiple functions in homeostasis and immunity. Neutrophils and IgA can interact via the IgA Fc receptor FcRI (CD89), leading to pro-or anti-inflammatory responses. Aims The aim of this review is to give a concise overview of the interplay between IgA, FcRI and neutrophils and to explore potential therapies for autoimmune diseases and cancer. Results Crosslinking of FcaRI by IgA-immune complexes yields potent neutrophil activation and pro-inflammatory effector functions, including the recruitment of neutrophils. This can lead to neutrophil accumulation and tissue destruction during IgA-autoantibody mediated diseases. Conversely, for cancer treatment, the myriad of powerful neutrophil effector functions after targeting FcaRI may contribute to effective immunotherapy. Conclusion By interfering with or actively promoting the interaction between IgA and FcaRI, therapies for multiple maladies could be developed