Granulomatosis with polyangiitis (Wegener) is characteristically associated with which antibody?

• A. p-ANCA
• B. c-ANCA
• C. Anti-dsDNA
• D. Anti-Smith

Answer: (B)

Granulomatosis with polyangiitis is most characteristically linked to antibodies against proteinase 3 (PR3), which produce a cytoplasmic staining pattern on immunofluorescence (c-ANCA). This pattern and target are highly associated with this disease, reflecting the necrotizing granulomatous and vasculitic process it causes. By contrast, p-ANCA corresponds to antibodies like MPO and is more typical of other vasculitides such as microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis. Antibodies like anti-dsDNA and anti-Smith are associated with systemic lupus erythematosus and are not characteristic of Wegener’s.