Interleukin-2 (IL-2, Proleukin)

March 2007     View PDF     En español

Interleukin-2 (IL-2) is a naturally occurring substance made by cells in your immune system. Its main function is to signal cells (most often CD4+ cells) to become active and reproduce.

A man-made version of IL-2 (aldesleukin, Proleukin) has been studied for over 20 years in HIV-positive people as a way to increase the number of CD4+ cells. It is approved by the Food and Drug Administration (FDA) for treating other conditions, though some people living with HIV have found ways to make it part of their overall treatment strategy. Whether or not IL-2 therapy helps people with HIV to live longer or preserves their ability to fight infections is the subject of two large international studies.

CD4+ cells are central to managing your body’s response to infections. In HIV disease, these cells become infected with HIV and eventually die or begin to function improperly. Over time, as the total number of these cells declines and their functions fail, the immune system gradually weakens and loses its ability to fight disease.

IL-2 stimulates CD4+ cells to become active and reproduce. This can help restore or maintain a normal number of CD4+ cells and might also improve their function.