Characterization of the interleukin 2 receptors (IL-2R) expressed on human natural killer cells activated in vivo by IL-2: association of the p64 IL-2R gamma chain with the IL-2R beta chain in functional intermediate-affinity IL-2R.

作者：Stephan D. Voss, Paul M. Sondel, Richard J. Robb · 发表于：The Journal of Experimental Medicine · 年份：1992 · DOI：10.1084/jem.176.2.531 · 被引用次数：135 · 研究领域：Immune Cell Function and Interaction、T-cell and Retrovirus Studies、T-cell and B-cell Immunology

Interleukin 2 (IL-2) receptors expressed on the surface of activated T cells and natural killer (NK) cells exhibit a variety of affinity states depending on their subunit composition. Low-affinity binding is associated with a 55-kDa alpha chain, intermediate-affinity binding with a 70-75-kD beta chain, and high-affinity binding with a bimolecular complex of the alpha and beta subunits. In a previous study of the IL-2 receptors expressed on NK cells obtained from cancer patients after in vivo IL-2 therapy, we documented a discrepancy between the level of beta chain and the level of intermediate-affinity IL-2 binding sites expressed on the cell surface. Based on this result, we postulated that formation of intermediate-affinity receptor sites required a component in addition to the beta chain, and that this component was present at limiting levels in the patient NK cells. In the present study we have examined the structure of the intermediate-affinity receptor complex using monoclonal antibodies that recognize the beta chain, but that do not interfere with its ability to bind IL-2. Evidence is presented establishing the physical association of a novel protein of 64 kD with the beta chain in intermediate-affinity IL-2 binding sites. This molecule, termed IL-2R gamma chain, coprecipitated with beta chains prepared from cells that had been incubated with IL-2, but was undetectable in immunoprecipitates prepared in the absence of IL-2. Examination of gamma chain expression in post-...