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
Langerhan's cells are: 
Select and explain. 
A. Phagocytic cells, B. Antigen presenting cells, C. Seen in auto immune conditions, D. Seen in chronic infection
B: Antigen presenting cells
Answer: B: Antigen presenting cells 
Explanation: 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