In order to activate helper/inducer T (CD41) lymphocytes, macrophages release: (A) Interleukin 1, (B) Interleukin 2, (C) Interleukin 3, (D) Interleukin 4
Answer is A. 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.