The Effect of l-Arginine on Porphyromonas gingivalis-Induced Phagocytosis of a Murine Macrophage-like Raw 264.7 Cell Line

The aim of this study was to determine the effect of l-arginine on Porphyromonas gingivalis-induced phagocytosis by RAW 264.7 cells. The cells were pretreated with l-arginine or d-arginine prior to incubation with either unopsonized or opsonized P. gingivalis. In other experiments, the cells were pretreated with l-arginine and various concentrations of NMLA (NG-monomethyl-l-arginine) prior to incubation with the bacteria. The phagocytosis was microscopically assessed and determined by the phagocytic index. The results showed that l-arginine, but not d-arginine enhances the ability of RAW264.7 cells to engulf the bacteria. The upregulatory effect of l-arginine on P. gingivalis-induced phagocytosis was abolished by NMLA. The results of the present study suggest that l-arginine may upregulate the P. gingivalis-induced phagocytic activity of RAW264.7 cells, perhaps, via modulation of nitric oxide synthase.