This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
The following interleukin is characterically produced in a TH1 response 
Select and explain. 
A. IL2, B. IL4, C. IL5, D. IL 10
A: IL2
Answer: A: IL2 
Explanation: Ref Robbins 7/e p198;8/e p195; 9/e p198 IL-2 has essential roles in key functions of the immune system, tolerance and immunity, primarily its direct effects on T cells. In the thymus, where T cells mature, it prevents autoimmune diseases by promoting the differentiation of ceain immature T cells into regulatory T cells, which suppress other T cells that are otherwise primed to attack normal healthy cells in the body. IL-2 enhances activation-induced cell death (AICD). IL-2 also promotes the differentiation of T cells into effector T cells and into memory T cells when the initial T cell is also stimulated by an antigen, thus helping the body fight off infections. Together with other polarizing cytokines, IL-2 stimulates naive CD4+ T cell differentiation into Th1 and Th2 lymphocytes while it impedes differentiation into Th17 and folicular Th lymphocytes