MPO-ANCA induces IL-17 production by activated neutrophils in vitro via classical complement pathway-dependent manner

The elevation of serum anti-neutrophil cytoplasmic autoantibodies (ANCA) is significantly associated with the progression of some patients with systemic vasculitis. Especially, myeloperoxidase-specific ANCA (MPO-ANCA) play a pivotal role in the progression of systemic vasculitis including crescentic glomerulonephritis. Here we demonstrated that MPO-ANCA-activated neutrophils allow the local environment to differentiate Th-17 cells through IL-6, IL-17A, and IL-23 production. We found a variety of elevated serum cytokines, especially IL-17A, in ANCA-mediated systemic vasculitis mice. Furthermore, activated peritoneal neutrophils in vitro also produced IL-17A and IL-23 in response to MPO-ANCA. Co-stimulation of fungal mannoprotein and complements significantly enhanced the MPO-ANCA-mediated IL-17A expression, but F(ab)(2)' fragments of MPO-ANCA diminished the cytokine response. These results suggest that the activated neutrophils produce IL-17A and IL-23 in response to MPO-ANCA via classical complement pathway, which initiate the first steps of chronic autoimmune inflammation by allowing the local environment to develop Th-17-mediated autoimmunity. (C) 2008 Elsevier Ltd. All rights reserved.