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': "Langerhan's cells are: \nSelect and explain. \nA. Phagocytic cells, B. Antigen presenting cells, C. Seen in auto immune conditions, D. Seen in chronic infection", 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is B (Antigen presenting cells) : Langerhan's cells are characteristic Antigen presenting cells Langerhan's cells are clear dendritic Q cells situated among the cells of stratum spinosum (slun). Q They are believed to be antigen processing cells. Q They are S100 positive Q on immunohistochemical studies. On electron microscopy: they lack melanosomesQ contain characteristic organelle, the Birbeck's granule.Q", 'role': 'assistant'}]