Effects of Cefodizime on Phagocytosis of COS-1 Ccells

ABSTRACT

PURPOSE: Cefodizime is a new third-generation cephalosporin which has a structure and immunomodutation properties similar to cefotaxime. Various studies on cefodizime have demonstrated the direct eradication of bacteria in cooperation with the host defense mechanism, particularly with phagocytosis. We evaluated the effects of cefodizime on the phagocytosis of COS-1 cells transfected with FcgammaRI/gammagamma or FcgammaRIIA cDNA. METHODS: Phagocytosis was measured using the in vitro COS-1 cell modeling system according to Schreiber's method. COS-1 cells, which lack endogenoous Fcgammareceptors but have phagocytic potential, were transfected with either FcgammaRI/gammagammaor FcgammaRIIA cDNA. COS-1 cells, as target cells, were treated with antibiotics for 1 or 24 hours and incubated for 30 min with IgG coated sheep RBCs. Adhered IgG coated sheep RBCs were removed after brief exposure to hypotonic phosphate buffered saline. Phagocytosis index (PI) was calculated as the number of ingested RBCs per 100 phagocytic cells after wright-Giemsa staining. RESULTS: COS-1 cells tranfected with FcgammaR (either FcgammaRI/gammagamma or FcgammaRIIA cDNA) showed the phagocytic activity against IgG coated sheep RBC, while untransfected COS-1 cells did not. After treatment with cefodizime, phagocytic activity of FcgammaRI/gammagammacDNA transfected COS-1 cells was significantly increased, while that of FcgammaRIIA cDNA transfected COS-1 cells did not. Marked enhancement of phagocytosis of COS-1 cells was observed after treatment with cefodizime, but was not observed with ceftriaxone or moxalactam. CONCLUSION: Cefodizime showed marked enhancement of phagocytic activity of FcgammaR transfected COS-1 cells. FcgammaRI seems to play an important role in the enhancement of phagocytosis. Further studies will be required.