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
[{'content': 'The test is used for: \nSelect and explain. \nA. Tuberculosis, B. Syphilis, C. Sarcoidosis, D. Hepatitis B', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The principles of interferon-gamma release assays (IGRAs). A sample of either (A) puriﬁed T cells (T-\xa0SPOT TB test) or (B) whole blood (QuantiFERON–TB Gold test) is incubated in the presence of antigens\xa0speciﬁc to Mycobacterium tuberculosis (MTB). The release of interferon-gamma (IFN-γ) by the cells is\xa0measured by enzyme-linked immunosorbent assay (ELISA). (ELISPOT = enzyme-linked immunosorbent\xa0spot assay).\nRef: Davidson Ed 22nd\xa0Pg 695', 'role': 'assistant'}]