Is defibrotide's activity on leukocytes adenosine-receptor mediated? An “in vitro” - “ex vivo” appraisal

Defibrotide both “in vitro” and “ex vivo” decreases PMN adhesion to nylon columns. This activity is blunted by 8-phenyltheophylline, a known blocker of adenosine A1 A2 receptors, suggesting that Defibrotide acts on that kind of receptors. Indomethacin, a blocker of PGI 2 synthesis, did not cancel DFT's activity, suggesting that PGI 2 is not involved in DFT's activity, at least under our experimental conditions. Non-PMN leukocytes behaved differently “ex vivo” than PMNs. DFT's activity was not blunted by 8-phenyltheophylline, suggesting that DFT acts on this kind of cell through a different mechanism. The “in vitro” experiment did not confirm “ex vivo” studies suggesting that in the “in vitro” experiment “something” is missing that is present in “ex vivo” experiments.