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': 'Delayed hypersensitivity involves: \nSelect and explain. \nA. Neutrophils, B. Monocytes, C. Eosinophils, D. Lymphocytes', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Lymphocytes (Ref: Ananthanarayan, 9th/e, p. 167 and 8th/e, p. 168)* Reaction is mediated by sensitized T-lymphocytes which, on contact with specific antigen, release lymphokines that cause biological effects on macrophages, leucocytes and tissue cells.* Delayed type by CD4 Th1 cell.", 'role': 'assistant'}]