A2A Adenosine Receptor Induction Inhibits IFN- Production in Murine CD4 T Cells

Incubation of purified C57BL/6 murine CD4 T lymphocytes with anti-CD3 mAb serves as a model of TCR-mediated activation and results in increased IFNproduction and cell surface expression of CD25 and CD69. We demonstrate here that signaling through the TCR causes a rapid (4-h) 5-fold increase in A2A adenosine receptor (AR) mRNA, which is correlated with a significant increase in the efficacy of A2AAR-mediated cAMP accumulation in these cells. A2AAR activation reduces TCR-mediated production of IFNby 98% with a potency order of 4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxytetrahydrofuran-2-yl)-9H-purin2-yl]prop-2-ynyl}cyclohexanecarboxylic acid methyl ester (ATL146e; EC50 0.19 0.03 nM) > 4-{3-[6-amino-9-(5-cyclopropylcarbamoyl-3,4-dihydroxytetrahydrofuran-2-yl)-9H-purin-2-yl]prop-2-ynyl}piperidine-1-carboxylic acid methyl ester (ATL313; 0.43 0.06 nM) > 5 -N-ethylcarboxamidoadenosine (3.5 0.77 nM) > 2-[4-(2-carboxyethyl)phenethylamino]-5 -N-ethylcarboxamidoadenosine (CGS21680; 7.2 1.4 nM) N-cyclohexyladenosine (110 33 nM) > 2-chloro-N-(3-iodobenzyl)-5 -N-methylcarboxamide (390 160 nM), similar to the potency order to compete for radioligand binding to the recombinant murine A2AAR but not the A3AR. The selective A2AAR antagonist, 4-(2-[7-amino-2-[2-furyl][1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl-amino]ethyl)phenol (ZM241385), inhibits the effect of ATL146e with a pA2 of 0.34 nM and also inhibits the effects of N -cyclohexyladenosine and 2-chloro-N-(3-iodobenzyl)-5 -N-methylcarboxamide. In CD4 T cells derived from A2AAR / and A2AAR / mice, the IFNrelease response to ATL146e is reduced by 100 and 50%, respectively, indicative of a gene dose effect. The response of T cells to the phosphodiesterase inhibitor, 4-(3 -cyclopentyloxy-4 -methoxyphenyl)-2-pyrrolidone (rolipram), is not affected by A2AAR deletion. We conclude that the rapid induction of the A2AAR mRNA in T cells provides a mechanism for limiting T cell activation and secondary macrophage activation in inflamed tissues. The Journal of Immunology, 2005, 174: 1073–1080.