Role of nitric oxide on in vitro human eosinophil migration

Eosinophils purified from the rat peritoneal cavity have been! found to con tain nitric oxide synthase (NOS) functionally coupled to a cyclic GMP trans duction pathway that is involved in in vitro eosinophil migration, but no s tudies on cell locomotion have been done with purified human eosinophils. T herefore, this study was carried out to investigate the effects of N-omega -nitro-L-arginine methyl ester (L-NAME; a non-selective NOS inhibitor), 1-( 2-trifluoromethylphenyl) imidazole (TRIM; a type I/type II NOS inhibitor), 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT; a selective type II NOS inhibitor), and 1H-[1,2,4]-oxidiazolo[4,3-a] quinoxalin-1-one (ODQ; a solub le guanylate cyclase inhibitor) on human eosinophil migration induced by N- formyl-methionyl-leucyl-phenylalanine (fMLP). Human eosinophils were purifi ed from peripheral blood of healthy volunteers using a Percoll gradient fol lowed by an immunomagnetic cell separator. Chemotaxis was evaluated using a 48-well microchemotaxis chamber. The fMLP (1.0 x 10(-7) M)-induced eosinop hil migration was reduced significantly by I-NAME (0.1 and 1.0 mM), whereas the inactive enantiomer N-omega-nitro-D-arginine methyl ester (D-NAME) had no effect. The inhibition by I-NAME was restored by sodium nitroprusside ( 0.25 mM). The NOS inhibitors AMT and TRIM (0.05 to 0.25 mM each) also marke dly attenuated fMLP-induced chemotaxis. Additionally, ODQ (0.01 to 0.5 mM) concentration-dependently inhibited fMLP-induced migration, and the inhibit ion was restored by 2.0 mM dibutyryl cyclic GMP. In conclusion, this study demonstrates that human eosinophils present a nitric oxide-cyclic GMP pathw ay that is involved in the in vitro locomotion of this cell type. (C) 2001 Elsevier Science Inc. All rights reserved.