Selective immobilization of human mononuclear phagocytes by benoxaprofen

Abstract

Benoxaprofen [2-(4-chlorophenyl)-cu-methyl-5-benzoxazoleacetic acid] is a potent antiinflammatory agent that effectively suppresses edema and the infiltration of leukocytes in animal models of acute and chronic inflammation (1,2). Benoxaprofen has prevented the development of adjuvant arthritis in rats and reduced the intensity of established lesions of 14-25 days duration (1). The influx of mononuclear leukocytes into the pleural cavity of rats in response to injections of dextran or carrageenan was inhibited to a greater extent than that of polymorphonuclear neutrophi1 leukocytes (PMNs) (2). That the migration of rat, guinea pig, and human mononuclear leukocytes is more susceptible to inhibition by benoxaprofen than the migration of PMNs, was confirmed in vitro by both glass capillary tube and Boyden chamber techniques (2-4). The results of the present study indicate that concentrations of benoxaprofen achieved routinely in humans by a standard anti-arthritis regimen suppress the enhanced migration of human monocytes and macrophages exposed to different stimuli significantly more than that of human neutrophils and T lymphocytes. The inhibition of human mononuclear phagocyte chemotaxis by benoxaprofen is attributable to a direct and reversible immobilizing effect, while the increased adherence induced by higher concentrations of benoxaprofen may contribute to the suppression of neutrophil chemotaxis. MATERIALS AND METHODSWe obtained the following materials from the specified suppliers: Eagle's minimal essential medium, fetal bovine serum, and Hank's balanced salt solution (HBSS) (M.A. Bioproducts, Walkersville, MD); Sephadex G-10 and Sephadex G-25, macromolecular dextran (Macrodex), and Ficoll-Hypaque (Pharmacia Fine Chemicals, Inc., Piscataway, NJ); 5 times recrystallized ovalbumin and concanavalin A (Con A) (Miles Laboratories, Inc., Elkhart, IN); 3-p and 8-p pore membrane filters (Sartorius Filters, Hayward, CA); 8-p channel filters (Nuclepore Corp., Pleasanton, CA); N-formyl-methionyl-leucyl-phenylalanine (fMLP) and a-thioglycerol (Sigma Chemical Co., St. Louis, MO), and chemotactic chambers with a 0.2-ml blind-end stimulus compartment (Neuroprobe, Inc., Bethesda, MD). Chemotactic fragments of the fifth component of human complement (C5fr) and leukotriene B4 were prepared and purified as described (4). Benoxaprofen was supplied by Lilly Research Laboratories (Indianapolis, IN) and was solubilized in HBSS immediately before use by titration with 1M sodium hydroxide to provide a I-mg/ml stock solution (pH 7.2).Isolation of human leukocytes. Neutrophils, mixed mononuclear leukocytes, and T lymphocytes were obtained from sodium citrate-anticoagulated venous blood of normal subjects (5,6). Suspensions of mixed leukocytes in HBSS containing 0.2 gm of ovalbumin/100 ml and 0.00% Tris (hydroxymethyl) ami-

Effects of benoxaprofen on the binding to and inactivation of leucoattractants by human polymorphonuclear leucocytesin vitro

“…In addition to preferential inhibitory activity for the enzyme 5'-lipoxygenase [4,5] benoxaprofen inhibits the migration of mononuclear leucocytes (MNL) from humans, rats and guinea-pigs in vitro [6,7]. The drug at therapeutic concentrations also inhibits the random and leucoattractant-induced migration of human polymorphonuclear leuco- [1,7]. We have previously reported that benoxaprofen, unlike other nonsteroidal anti-inflammatory drugs (NSAID's), increases the spontaneous membrane-associated oxidative metabolism of human PMNL in vitro [1].…”

Anti‐inflammatory Action of Fenflumizole in Man: Suppression of Monocyte Chemotaxis ex Vivo

“…acetylsalicylic acid (Goetzl & Valone 1982) and indomethacin (Goetzl & Valone 1982;Nielsen & Bennedsen 1982), do not suppress monocyte chemotaxis. In contrast, inhibitors of lipoxygenase activity often inhibit leukotaxis (Goetzl & Valone 1982). Fenflumizole has been shown to exert some lipoxygenase inhibitory activity (Broodley, personal communication), which may explain its influence on monocyte migration as well.…”

“…The inhibitory effect is insufficiently explained by its cyclooxygenase inhibitory activity, since NSAIDs with classical cyclooxygenase inhibitory activity, e.g. acetylsalicylic acid (Goetzl & Valone 1982) and indomethacin (Goetzl & Valone 1982;Nielsen & Bennedsen 1982), do not suppress monocyte chemotaxis. In contrast, inhibitors of lipoxygenase activity often inhibit leukotaxis (Goetzl & Valone 1982).…”