This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Pathology
TH1 is involved in w hich type of hypersensitivity? 
Select and explain. 
A. Type 1, B. Type 2, C. Type 3, D. Type 4
D: Type 4
Answer: D: Type 4 
Explanation: * Delayed type of hypersensitivity is mediated by T cell dependant effector mechanisms involving both CD4+ TH1 cells and CD8 Cytotoxic T cells.* Antibodies do not play a role in type IV hypersensitivity reactions. The activated TH1 cells release Cytokines that will cause accumulation and activation of macrophages which will cause local damage.* TH 2 cells release IL-4 and are involved in Type 1 Hypersensitivity reaction.