This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non Hodgkin Iymphoma, Subject name: Pathology
[{'content': 'Mantle cell lymphomas are positive for all of the following, except: \nSelect and explain. \nA. CD 23, B. CD 20, C. CD 5, D. CD 43', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mantle cells lymphomas are usually CD23 negative. They are positive for CD5, CD20 and CD43.', 'role': 'assistant'}]