Search for adenosine A_2A spare receptors on peripheral human lymphocytes

详细信息    查看全文

• 作者：Laurent Jacquin ; Fr茅d茅ric Franceschi ; Youlet By ; Jos茅e-Martine Dur ; -Gorde ; Jocelyne Condo ; Jean-Claude Deharo ; Pierre Michelet ; Emmanuel Fenouillet ; R茅gis Guieu ; Jean Ruf
• 关键词：Adenosine A2A receptor ; Agonist ; Lymphocyte ; mAb ; Spare receptor
• 刊名：FEBS Open Bio
• 出版年：2013
• 年：2013
• 卷：3
• 期：Complete
• 页码：1-5
• 全文大小：454 K

文摘

Some ligand-receptor couples involve spare receptors, which are apparent when a maximal response is achieved with only a small fraction of the receptor population occupied. This situation favours cross-reactions with low-affinity ligands, which may be detrimental for cell signaling. In the case of the adenosine A_2A receptors (A_2AR), which have an immunosuppressive effect on lymphocytes through cAMP production, the presence of spare A_2AR remains to be established. We examined the situation using patients over-expressing lymphocyte A_2AR and an agonist-like mAb to A_2AR. We found that maximal mAb binding and functional response varied among the patients whereas the dissociation constant and half-maximal effective concentration had similar mean values (0.19 and 0.18 渭M, respectively). Lymphocyte A_2AR expression was correlated to plasma adenosine level and A_2AR occupation but not to A_2AR response. These results are consistent with a lack of a reserve of functional A_2AR on human lymphocytes as a general rule and suggest that the amount and functional state of the expressed A_2AR determine the maximal level of the lymphocyte response to adenosine.