Effects of grepafloxacin, a newly developed fluoroquinolone, on neutrophil functions.

New quinolone (NQ) antimicrobials have strong bactericidal effects and a broad spectrum of antimicrobial activities. In this study, we investigated the in vitro effects of grepafloxacin (GPFX), a newly developed fluoroquinolone, on neutrophil functions. Superoxide production by neutrophils was measured using the ferricytochrome reduction assay. Enhancement of Superoxide production was observed in the presence of more than 10μg/ml of GPFX when stimulated with formyl-methionyl-leucyl-phenylalanine (FMLP) and more than 3μg/ml when stimulated with phorbol myristate acetate (PMA) . Neutrophils pretreated with more than 30μg/ml of GPFX also showed enhancement of superoxide production in response to both of the two stimuli. On the other hand, GPFX had no effect on FMLP-induced neutrophil chemotaxis at any of the concentrations (1 to 100μg/ml) . These results suggest that GPFX facilitates the improvement of bacterial infections with the combination of its bactericidal effect and the activation of neutrophils in vivo.