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
Delayed hypersensitivity involves: 
Select and explain. 
A. Neutrophils, B. Monocytes, C. Eosinophils, D. Lymphocytes
D: Lymphocytes
Answer: D: Lymphocytes 
Explanation: 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.