CURRENT THERAPEUTIC RESEARCH VOL. 54, NO. 2, AUGUST1993 EFFECT OF IMIDAZOLE SALICYLATE ON THE RESPIRATORY BURST OF POLYMORPHONUCLEAR LEUKOCYTES A. KANTAR,1 N. OGGIANO, 1 R. GABBIANELLI, 1 P. L. GIORGI, 1 AND M. BIRAGHI 2 IPediatric Clinic, University of Ancona, Ancona, and 2Medical Department, VALEAS, Milan, Italy ABSTRACT The effect of imidazole salicylate (IS), an organic salt of imidazole and salicylic acid, on the respiratory burst of polymorphonuclear leu- kocytes (PMNs) was investigated using a chemiluminescence (CL) as- say. Luminol- and lucigenin-amplified CL of PMNs stimulated with N-formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA) were evaluated in the absence or presence of 1 to 4 ~tg/ml of IS. Luminol-amplified CL of PMNs activated with FMLP was significantly reduced in the presence of IS, whereas no significant effect was observed on PMA-stimulated PMNs. Lucigenin- amplified CL of PMA-stimulated PMNs was significantly inhibited by IS. CL of the xanthine/xanthine oxidase system was abolished in the presence of IS. These results suggest that IS is a scavenger of the superoxide anion and that it can influence the respiratory burst of PMNs, probably by interacting with the plasma membrane. INTRODUCTION There is little argument that the products of activated polymorphonuclear leukocytes (PMNs) damage tissue. 1 This is especially true in the case of inflammatory reactions that feature an infiltration of PMNs. Activated PMNs injure tissue by releasing products stored in granules and generat- ing new factors, including oxygen species. The latter process, known as the respiratory burst, is initiated when, after a suitable stimulus, molecular oxygen undergoes a one-electron reduction to superoxide anion at the ex- pense of nicotinamide adenine dinucleotide phosphate (NADPH). 2 This re- action is mediated by a multicomponent enzyme system, known as respi- ratory burst oxidase. 3 In studies of the inflammatory injury of tissue, oxidants, which are generated by stimulated PMNs, appear to participate significantly in the attack on cells and supporting tissue. 4 Nonsteroidal anti-inflammatory drugs (NSAIDs) act by inhibiting the synthesis and release of prostaglan- dinsS'6; however, this may not account for all the effects of NSAIDs at all Address correspondenceto: Dr. A. Kantar, Pediatric Clinic, University of Ancona, via Corridoni 11, 1-60123 Ancona,Italy. Received for publication on June 1, 1993. Printed in the U.S.A. Reproductionin whole or part is not permitted. 241 0011-393X/93/$3.50