C- ANCA positivity indicates, antibody formed against which of the following?: (A) Proteinase 3, (B) Myeloperoxidase, (C) Cytoplasmic antinuclear Antibody, (D) Anti centromere Antibody
Answer is A. C-ANCAs (Cytoplasmic anti-neutrophil cytoplasmic antibodies), are a type of autoantibody formed against proteinase 3. P-ANCA (Perinuclearanti-neutrophil cytoplasmic antibodies) are antibodies directed against myeloperoxidase. Ref: Harrison's Principles of Internal Medicine, 16th Edition, Page 2002; Thurlbeck's Pathology Of The Lung, William M. Thurlbeck, 3rd Edition, Page 372; Rheumatology Secrets, Sterling G. West, 2nd Edition, Page 226.