title: Host defense against bacterial keratitis.
abstract: OBJECTIVE
  To define factors that protect the eye from Staphylococcus aureus keratitis and limit tissue damage once keratitis occurs.
  
  
  METHODS
  Rabbit tears were analyzed for bactericidal and phospholipase A(2) (PLA(2)) activities on S. aureus. Inhibition by spermidine of PLA(2) anti-staphylococcal activity in tears was tested in vitro and in vivo. Rabbits immunized with heat-inactivated alpha-toxin were challenged with intrastromal injection of S. aureus.
  
  
  RESULTS
  Arachidonic acid was cleaved from S. aureus by purified PLA( 2) or rabbit tears. Spermidine inhibited these reactions in vitro and facilitated keratitis in vivo. PLA(2) activity decreased with advanced age and shortly following sleep, but increased with keratitis. Antibody to alpha-toxin significantly reduced corneal damage and epithelial cell sloughing during keratitis.
  
  
  CONCLUSIONS
  PLA(2) is a major host-defense component of rabbit tears. Alpha-toxin is a major mediator of corneal damage, and antibody to alpha-toxin reduces pathologic changes during keratitis.
authors.affiliation: Department of Microbiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. rocall@lsuhsc.edu
authors.forename: Richard J
authors.initials: RJ
authors.lastname: O'Callaghan
authors.forename: Dalia O
authors.initials: DO
authors.lastname: Girgis
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Dajcs
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Sloop
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D003319:Corneal Stroma / Q000382:microbiology; D003320:Corneal Ulcer / Q000276:immunology* / Q000382:microbiology* / Q000517:prevention & control; D015818:Eye Infections, Bacterial / Q000276:immunology* / Q000517:prevention & control; D007113:Immunity, Innate / Q000502:physiology; D007114:Immunization; D010741:Phospholipases A / Q000378:metabolism; D011817:Rabbits; D013095:Spermidine / Q000494:pharmacology; D013203:Staphylococcal Infections / Q000276:immunology* / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000502:physiology*; D013666:Tears / Q000201:enzymology; D010738:Type C Phospholipases / Q000008:administration & dosage
chemical_list: D016718:Arachidonic Acid; D010741:Phospholipases A; D010738:Type C Phospholipases; D013095:Spermidine