Discovery of interleukin-2 (IL-2)



In the 1970s, researchers sought to define whether retroviruses are causative agents of human diseases, including cancers. In order to discover and study human retroviruses, researchers first needed to identify a way to grow and maintain T lymphocytes, or T-cells, long-term in the lab.


IRP researchers led by Robert Gallo, M.D., found a way to successfully grow T-cells in culture for more than nine months. They accomplished the feat by first stimulating lymphocytes with phytohemagglutinin, a protein found in plants, and then examining for the production of potential growth factors in the culture fluid. The team identified T-cell growth factor (TCFG), now known as interleukin-2 (IL-2).


The discovery and purification of IL-2 allowed researchers to grow T-cells and study their immunology, which led to the discovery of human T-cell leukemia virus (HTLV), the first retrovirus identified in humans.


Morgan DA, Ruscetti FW, Gallo R (1976). Selective in vitro growth of T lymphocytes from normal human bone marrows. Science. 193(4257):1007–8.

Mier JW, Gallo RC (1980). Purification and some characteristics of human T-cell growth factor from phytohemagglutinin-stimulated lymphocyte-conditioned media. Proc Natl Acad Sci U S A. 77(10):6134-8.

View All Health Topics

This page was last updated on Friday, August 11, 2023