A₁ and A₃ ARs mediate adenosine-induced NETosis. Control neutrophils were incubated with adenosine (Ado) in the presence or absence of different AR antagonist for 3 to 4 hours. (A) Percentage of NETs was quantified (number of NETs/total number of neutrophils + NETs). Results are representative of 4 different experiments. (B) Representative confocal images of NET formation after treatment with an AR antagonist. Blue represents Hoechst; red is myeloperoxidase (MPO). Scale bar, 50 µm. (C) Neutrophils were incubated with adenosine, A₁AR (5-deoxy-(±)-ENBA [Cl-ENBA]) or A₃AR (MRS5698) agonists for 2 hours. NETs were quantified. (D-E) NETs were quantified after different concentrations of an A₁AR agonist and/or in the presence of specific A₁AR antagonists. *P < .05, **P < .01, ***P < .001, ****P < .0001, Mann-Whitney U test. Results are the means ± SEM of n = 4.