Immunopathology of Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) constitutes a group of rare diseases characterized by autoimmune-associated inflammation and vessel damage. Based on the clinical manifestations and involvement of immune components, three disease syndromes are distinguished: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). In this review, we present the current data on the epidemiology, the clinical manifestations of each syndrome, and the most up-to-date classification criteria. The role of the underlying genetic and epigenetic abnormalities, as well as their interplay, is described. The immunological diversification of AAV is also described, with a focus on the immune cell dysfunctions detected in patients. In conclusion, we emphasize the urgent need to unravel the sophisticated mechanisms of this disease, which would enable the development of new, effective therapeutic strategies.