<prompt> In order to activate helperinducer T CD41 lymphocytes, macrophages releaseInterleukin 1Interleukin 2Interleukin 3Interleukin 4  <response>: 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. 