title: Plasma complement C5 protects endothelial cells from polymorphonuclear neutrophil-derived, H2O2-mediated cytotoxicity.
abstract: BACKGROUND
  In vitro studies suggest that polymorphonuclear neutrophils (PMN) can damage endothelial cells (EC) by releasing hydrogen peroxide. In vivo this can lead to anasarca secondary to capillary leakage of fluid, protein, and electrolytes. The result is multiple organ dysfunction syndrome, which is associated with high mortality. In vivo, circulating PMN-EC interactions take place in the presence of plasma, and we have shown previously that plasma affords protection to EC from PMN-mediated damage.
  
  
  METHODS
  Human umbilical vein endothelial cells were primed with cytokines, cultured to a confluent monolayer, and coincubated with normal human PMNs. Cytotoxicity was assayed by gamma scintigraphy, plasma C5 was determined by sepharose column elution, and H(2)O(2) was assayed by R-Phycoerythrin fluorescence.
  
  
  RESULTS
  Addition of C5, but not C3, to RPMI resulted in EC cytoprotection equivalent to adding whole serum. Removal of C5 from serum using F(ab')(2) rabbit IgG anti-human C5 coupled to CNBr-activated 4 sepharose beads resulted in significant loss of EC cytoprotection against H(2)O(2)-mediated damage, whereas adding back C5 restored the cytoprotection. C5 also reduced H(2)O(2)-mediated destruction of R-Phycoerythrin.
  
  
  CONCLUSIONS
  The data suggest that the protection of EC against hydrogen peroxide-mediated damage is partly mediated through complement component C5.
authors.affiliation: LD MacLean Surgical Laboratories, McGill University Health Center, 687 Pine Avenue West, Montreal, Quebec H3A 1A1, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Giroux
authors.forename: D E
authors.initials: DE
authors.lastname: Swartz
authors.forename: N V
authors.initials: NV
authors.lastname: Christou
mesh_terms: D000818:Animals; D003167:Complement Activation / Q000187:drug effects / Q000276:immunology; D003182:Complement C5 / Q000276:immunology* / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects* / Q000276:immunology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000276:immunology* / Q000293:injuries*; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000009:adverse effects* / Q000276:immunology*; D066298:In Vitro Techniques; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology*; D016877:Oxidants / Q000009:adverse effects* / Q000276:immunology*; D010949:Plasma / Q000276:immunology*; D011817:Rabbits; D014471:Umbilical Veins / Q000187:drug effects / Q000276:immunology / Q000293:injuries
chemical_list: D003182:Complement C5; D016877:Oxidants; D006861:Hydrogen Peroxide