Pathological Roles of Interleukin-15 in Adult T-cell Leukemia

Abstract

Interleukin-15 (IL-15) is a 14-kDa glycoprotein belonging to the same four helix bun-dle-cytokine family as IL-2. Although the biological activity of L-15 in vitro has been studied extensively. its physiological role is still obscure. The receptors for IL-15 and IL-2 consist of three subunits, an unique α chain and shared β and γ chains. Since β and γ chains transduce the signals from the receptors, both cytokines share similar biologic functions, although IL-15 and IL-2 do not have sequence homology. The α chains function to increase binding affinity for each cytokines. Adult T-cell leukemia (ATL) cells constitutively express the IL-2 receptor (IL-2R) a and expression is believed to be essential in the early stages of disease development. We have recently shown that ATL cells also express the complete form of IL-15R including the α chain, and that ATL cells proliferate in response to exogenous IL-15. Since the mRNA of IL-15 is ubiquitous and is detected in many tissues and cells, it is possible that IL-15R stimulation is involved in the development and progression of An. Here, we review recent studies on IL-15 and IL-15R and their association with ATL and other lymphoproliferative disorders.

Key Words:

• role of interleukin-15
• IL-15
• adult T-cell leukemia