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': 'All are B-cell marker except: \nSelect and explain. \nA. CD15, B. CD19, C. CD21, D. CD24', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Direct lines from Wintrobes hematology..CD-15 is expressed on neutrophils, esinophils and monocytes but not on on platelets,lymphocytes and erythrocytes.About option (d)CD24 is expressed on B cell activation and differentiation and is lost at the plasma cell stage. It is also present ion granulocytes and thymocytes but not on mature T cells.data shows its increased levels are associated with colon/breast and pancreatic cancer.( ref Robbins 7th/670,9/e590)', 'role': 'assistant'}]