Neutrophil-Mediated Regulation of Innate and Adaptive Immunity: The Role of Myeloperoxidase

Figure 3

Summary of MPO involvement in neutrophil functions in innate and adaptive immunity. MPO is involved in microbe clearance by neutrophils both intracellularly (via the production of HOCl) and extracellularly (via the release of NETs). On the other hand, the release of MPO-containing NETs can result in the generation of autoimmunity against MPO and subsequent development of ANCA-associated vasculitis. HOCl that is produced outside of activated neutrophils following MPO release can cause significant tissue damage. In contrast, MPO that is released by neutrophils in lymph nodes can inhibit DC activation and thus generation of adaptive T cell responses, thus attenuating organ injury. HOCl, hypochlorous acid; H₂O₂, hydrogen peroxide; Cl, chloride; NETs, neutrophil extracellular traps; DC, dendritic cell; ANCA, anti-neutrophil cytoplasmic antibody.