Neutrophils and B lymphocytes in ANCA-associated vasculitis

The pathogenesis of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is unknown but is most consistent with a primary role for neutrophils in the acute injury. Thus, neutrophils are cardinal cells in the pathophysiological process in AAV because they are both effector cells responsible for endothelial damage and targets of autoimmunity. In addition, because of their capacity to synthesize a wide variety of cytokines and chemokines, neutrophils can be considered as important modulators of the inflammatory and potentially of the autoimmune process. ANCA directed against two main autoantigens, namely proteinase 3 and myeloperoxidase, are likely to play a modulatory role in the inflammatory process. Interestingly, neutrophils are an important source of lymphocyte stimulator (BLy), a cytokine that plays a fundamental role in B-cell physiology, including differentiation, proliferation and immunoglobulin production. The issue of B-cell activation and/or dysregulation in vasculitis will be discussed.