This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transplantation, Subject name: Surgery
[{'content': 'In order to activate helper/inducer T (CD41) lymphocytes, macrophages release \nSelect and explain. \nA. Interleukin 1, B. Interleukin 2, C. Interleukin 3, D. Interleukin 4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Interleukin 1 (IL-1) is a thymocyte mitogen produced by activated macrophages as well as many other types of cells (e.g., monocytes, dendritic cells, Langerhans cells, neutrophils, microglial cells). It induces interleukin 2 production by the helper T cell, which initiates a cascade of immunoregulatory and inflammatory functions.', 'role': 'assistant'}]