Effect of pirprofen on polymorphonuclear leukocyte functions in vitro

The action of the new non-steroidal anti-inflammatory drug (NSAID) pirprofen on different functions of human polymorphonuclear leukocytes (PMNs) has been studied. The chemotaxis of PMNs was found to be affected by pirprofen in a dose-dependent fashion; at a concentration of 2 micrograms/ml (10 times lower than the therapeutic blood levels) it significantly inhibited PMN locomotion toward two different chemoattractants. Moreover pirprofen inhibited the chemiluminescent response in a dose- and stimulus-dependent way. In fact the drug inhibited the chemiluminescence induced by the soluble stimuli FMLP or PMA, but it was ineffective when zymosan particles were used. The phagocytosis and adhesion functions of the PMNs were not modified by pirprofen at the concentrations tested. These experimental results suggest that a reduction of the accumulation and activation of inflammatory cells in tissues may represent another way, together with cyclooxygenase inhibition, by which pirprofen realizes its antiinflammatory activity in vivo.