This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'The most impoant source of histamine \nSelect and explain. \nA. Mast cells, B. Eosinophil, C. Neutrophils, D. Macrophages', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ref Robbins 8/e p57,9/e p83 Histamine is synthesized in all tissues, but is paicularly abundant in skin, lung and gastrointestinal tract. Mast cells, which are present in many tissues, are a prominentsource of histamine, but histamine is also secreted by a number of other immune cells.', 'role': 'assistant'}]