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: Unknown
[{'content': 'Nude mice is able to accept xenograft because they lack: \nSelect and explain. \nA. T cells, B. B cells, C. NK cells, D. LAK cells', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ref. Textbook of Microbiology and Immunology BY Parija. Page. 162\n\xa0\nNude Mice\n\nCongenitally athymic nude mice (nu/nu) are presented as a model for the study of cell-mediated immunologic deficiencies.\nThese mice possess a vestigial thymus which is incapable of producing mature T-cells as shown by a decreased lymphocyte population carrying the theta antigen and depleted 'thymus-dependent' areas in their peripheral lymphoid organs.\nThey have T-cell precursors in their bone marrow. Nude mice lack 'thymosin', a thymic factor secreted by the epithelial cells of the thymus.\nThey also have impaired T-cell functions as demonstrated by an absence of delayed hypersensitivity reactions, an inability to reject skin allografts and a decreased antibody response to some T-dependent antigens", 'role': 'assistant'}]