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': 'True about MHC class II \nSelect and explain. \nA. Not involved in innate immunity, B. Cytotoxic T cell involved, C. Present in nucleated cells, D. Present in B cells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref Robbins 7/e p203; 9/e p194-195 The main function of major histocompatibility complex (MHC) class IImolecules is to present processed antigens, which are derived primarily from exogenous sources, to CD4(+) T-lymphocytes. MHC class II molecules thereby are critical for the initiation of the antigen-specific immune response.', 'role': 'assistant'}]