Quinolones alter defense reactions mediated by macrophages

The innate host defense system is regulated in part by the number and activation of the function of neutrophils and macrophages. The immunological effects of a variety of quinolones on host defense functions of macrophage are reported. Ofloxacin (OFLX), lomefloxacin (LFLX), tosufloxacin (TFLX), fleroxacin (FLRX), sparfloxacin (SPFX) and levofloxacin (LVFX) significantly inhibited phagocytosis of Escherichia coli by macrophages. Moreover, TFLX markedly potentiated the expression of the adhesion molecule Mac-1 by macrophages. No significant alteration was detected in the adherence and the expression of adhesion molecule Mac-1 in macrophages treated with the other quinolones. In contrast, OFLX, LFLX, TFLX, and LVFX were effective in significantly increasing the production of hydrogen peroxide, while the other agents did not. These results suggest that the quinolones at a therapeutic concentration differentially affect phagocytosis, adhesion and the production of hydrogen peroxide by macrophages. (C) 2001 Elsevier Science B.V. All rights reserved.