This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'c-ANCA positivity indicates, antibody formed against: \nSelect and explain. \nA. Proteinase 3, B. Myeloperoxidase, C. Cytoplasmic antinuclear antibody, D. Anti centromere antibody', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Proteinase 3): Proteinase - 3 (a 29 - kDA serine proteinase) present in neutrophil azurophilic granules is the major c-ANCA antigen. Major c-ANCA antigen Proteinase 3 (PR-3) Major p - ANCA antigen Myeloperoxidase (MPO)', 'role': 'assistant'}]