This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'T4/T8 ratio reversal is seen in - \nSelect and explain. \nA. T-cell lymphoma, B. Hairy cell leukemia, C. AIDS, D. Infectious mononucleosis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The T-Lymphocyte Helper/Suppressor Profile (Helper/Suppressor ratio, T4:T8 ratio, CD4:CD8 ratio) is a basic laboratory test in which the percentage of CD3-positive lymphocytes in the blood positive for CD4 (T helper cells) and CD8 (a class of regulatory T cells) are counted and compared. Normal values (95% confidence intervals) are approximately 30-60% CD4 and 10-30% CD8 depending on age (ratio 0.9 to 3.7 in adults). One reason for abnormal results is the loss of CD4-positive cells to the Human Immunodeficiency Virus (HIV) infection. The loss of CD4-positive cells to HIV infection can result in various distoions in the ratio, as in the initial period, production of HIV specific CD8 positive cells will cause a large fall in the ratio Reff: www.mayo clinic.com', 'role': 'assistant'}]