OxyFile #102

TI:  Role of Hydrogen Peroxide in Neutrophil-mediated Destruction 
     of Cultured Endothelial Cells.

DT:  January 2, 1981

AU:  S.J. Weiss, J. Young, A.F. LoBuglio, A. Slivka

SO:  J. Clin. Invest, Vol. 68, Sept 1981, 714-721

AB:  Human neutrophils stimulated with phorbol myristate acetate 
     were able to destroy suspensions or monolayers of cultured 
     human endothelial cells.  Neutrophil-mediated cytotoxicity 
     was related to phorbol myristate acetate concentration, time 
     of incubation and neutrophil number.  Cytolysis was 
     prevented by the addition of catalase, while superoxide 
     dismutase had no effect on cytotoxicity.  The addition of 
     the heme-enzyme inhibitors, azide or cyanide, markedly 
     stimulated neutrophil-mediated damage while exogenous 
     myeloperoxidase failed to stimulate cytolysis.  Neutrophils 
     isolated from patients with chronic granulomatous disease 
     did not destroy the endothelial cell targets while 
     myeloperoxidase-deficient neutrophils successfully mediated 
     cytotoxicity.  Endothelial cell damage mediated by the 
     myeloperoxidase deficient cells was also inhibited by 
     catalase but not superoxide dismutase.  The addition of 
     purified myeloperoxidase to the deficient cells did not 
     stimulate cytotoxicity.  Glucose-glucose oxidase, an enzyme 
     system capable of generating hydrogen peroxide, could 
     replace the neutrophil as the cytotoxic mediator.  The 
     addition of myeloperoxidase at low concentrations of glucose 
     oxidase did not increase cytolysis, but at the higher 
     concentrations of glucose oxidase it stimulated 
     cytotoxicity.  The destruction of endothelial cells by the 
     glucose oxidase-myeloperoxidase system was inhibited by the 
     addition of hypochlorous acid scavengers.  In contrast, 
     neutrophil-mediated cytolysis was not effectively inhibited 
     by the hypochlorous acid scavengers.  Based on these 
     observations, we propose that human neutrophils can destroy 
     cultured human endothelial cells by generating cytotoxic 
     quantities of hydrogen peroxide.