Immunomodulatory action of levofloxacin on cytokine production by human peripheral blood mononuclear cells.

Levofloxacin (LVFX), the bacteriologically active isomer of ofloxacin, is a fluorinated quinolone. LVFX suppressed the proliferative activity of peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin (PHA). LVFX increased interleukin-2 (IL-2) production by PBMC stimulated with PHA in a dose-dependent manner, with more than 10 micrograms/ml of LVFX causing a significant increase. The granulocyte-macrophage colony-stimulating factor and soluble IL-2 receptor production by PHA-stimulated PBMC was suppressed at high concentrations of LVFX. Interleukin-1 beta production by lipopolysaccharide-stimulated PBMC was suppressed in a concentration-dependent manner by LVFX, and tumor necrosis factor-alpha production was suppressed at only the highest concentration. In contrast, interleukin-8 production was little affected by LVFX. These results show that LVFX has an immunomodulatory action on cytokines production by PBMC independent of its antimicrobial activity.