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': 'Which is not pyrogenic - \nSelect and explain. \nA. IL-1, B. TNF-a, C. IL-4, D. IL-6', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pyrogenic cytokines such as tumor necrosis factor (TNF), interleukin (IL)-1, IL-6, and interferons into the bloodstream in response to exogenous pyrogens. Reff: www.mayoclinic.com', 'role': 'assistant'}]