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Updated: Aug 8, 2026

Ex vivo Expansion of Tumor-reactive T Cells by Means of Bryostatin 1/Ionomycin and the Common Gamma Chain Cytokines Formulation
Published on: January 15, 2011
Internalization of interleukin 2 is mediated by the beta chain of the high-affinity interleukin 2 receptor
High-affinity IL-2-R correspond to a membrane receptor complex composed of two different IL-2-binding proteins, the Tac antigen (alpha chain) and a 70-75 kD beta chain. Using cell lines that express either the alpha or the beta protein, we demonstrate that IL-2 internalization occurs when ligand is bound to the isolated beta chain, but not when it is bound to the isolated alpha chain. The kinetics of IL-2 internalization mediated by the intermediate-affinity beta chain were nearly identical to those of the high-affinity alpha/beta heterodimer (t1/2 of 10-15 min), and each type of receptor targeted the bound IL-2 for intracellular degradation in lysosomes. The beta chain thus appeared to provide the essential element necessary for ligand internalization by both types of IL-2-R.
High-affinity IL-2-R correspond to a membrane receptor complex composed of two different IL-2-binding proteins, the Tac antigen (alpha chain) and a 70-75 kD beta chain. Using cell lines that express either the alpha or the beta protein, we demonstrate that IL-2 internalization occurs when ligand is bound to the isolated beta chain, but not when it is bound to the isolated alpha chain. The kinetics of IL-2 internalization mediated by the intermediate-affinity beta chain were nearly identical to those of the high-affinity alpha/beta heterodimer (t1/2 of 10-15 min), and each type of receptor targeted the bound IL-2 for intracellular degradation in lysosomes. The beta chain thus appeared to provide the essential element necessary for ligand internalization by both types of IL-2-R.
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