Interleukin-2 Receptor β Chain in Leukemias and Lymphomas

Abstract

Interleukin-2 (IL-2) is an immunoregulatory lymphokine that plays a critical role in the proliferation and activation of T cells. The action of IL-2 is mediated by binding to IL-2 receptors (IL-2Rs) on the cell surface. IL-2Rs are composed of at least two distinct IL-2 binding protein: the IL-2Rα chain (Tac peptide, p55) and the IL-2Rβ chain (p70–75). Expression of the α chain or the β chain alone results in low-affinity or intermediate-affinity IL-2R, respectively, whereas high-affinity IL-2R is formed when both the α and β chains are expressed. The expression of IL-2Rs has been demonstrated on various hematopoietic malignant cells. Both the IL-2Rα and β chains are expressed by most adult T-cell leukemia cells. The IL-2Rβ chain alone is constitutively expressed by abnormally expanded granular lymphocytes (GLs) from patients with GL-proliferative disorders or related conditions. The IL-2Rα chain alone is expressed by most hairy cell leukemia cells. However, there is a diversity of views on the expression of the IL-2 chains on other hematopoietic malignant cells. Since IL-2 is now under consideration in the clinical treatment of hematopoietic malignancies, further investigations to clarify the significance of IL-2R expression in leukemias and lymphomas are needed.

Key Words:

• Interleukin-2 receptor
• leukemia
• lymphoma