Which antibodies are very useful diagnostic markers in non-infectious vasculitis?

Which antibodies are very useful diagnostic markers in non-infectious vasculitis?

• A. ANA
• B. CRP
• C. ANCA
• D. RF

Answer: (C)

ANCA antibodies are very useful diagnostic markers in non-infectious vasculitis because they target enzymes inside neutrophils (such as proteinase 3 and myeloperoxidase) and are strongly associated with ANCA‑associated small-vessel vasculitides. Their presence supports diseases like granulomatosis with polyangiitis and microscopic polyangiitis, and can be detected by immunofluorescence and ELISA (c‑ANCA/PR3-ANCA and p‑ANCA/MPO‑ANCA patterns). This makes them more specific for these vasculitides than general inflammatory markers or non-specific autoimmune antibodies. In contrast, CRP is a general marker of inflammation, ANA is a broad autoantibody seen in many autoimmune diseases, and RF is associated with rheumatoid arthritis—not specific for vasculitis. Be aware that ANCA is not present in all cases of vasculitis and some conditions can be ANCA-negative, so clinical context and sometimes biopsy remain essential.

ANCA antibodies are very useful diagnostic markers in non-infectious vasculitis because they target enzymes inside neutrophils (such as proteinase 3 and myeloperoxidase) and are strongly associated with ANCA‑associated small-vessel vasculitides. Their presence supports diseases like granulomatosis with polyangiitis and microscopic polyangiitis, and can be detected by immunofluorescence and ELISA (c‑ANCA/PR3-ANCA and p‑ANCA/MPO‑ANCA patterns). This makes them more specific for these vasculitides than general inflammatory markers or non-specific autoimmune antibodies.

In contrast, CRP is a general marker of inflammation, ANA is a broad autoantibody seen in many autoimmune diseases, and RF is associated with rheumatoid arthritis—not specific for vasculitis. Be aware that ANCA is not present in all cases of vasculitis and some conditions can be ANCA-negative, so clinical context and sometimes biopsy remain essential.