Interleukin-2 and its Receptors in Human Solid Tumours: Immunobiology and Clinical Significance

Human carcinomas were found to express IL-2 R and to produce, but not to secrete, IL-2. Intermediate affinity IL-2Rβγ detected on the surface and in the cytoplasm of carcinoma cells binds exogenous IL-2 at the nanomolar or micromolar concentrations and mediates cell cycle arrest (CCA) possibly through the upregulation of the CDK inhibitor p27kipl expression. In contrast, IL-2Rα is modestly expressed on the cell surface, and it may be involved in the intracrine pathway of delivering endogenous IL-2 to the cell surface. IL-2 is a growth factor for human carcinomas, and as it binds to the high-affinity IL-2R, it promotes cellular proliferation by suppressing expression of p27kipl. It also prot…