title: Time-related changes in equine neutrophils after experimental endotoxemia: myeloperoxidase staining, size, and numbers.
abstract: BACKGROUND
  Neutrophil myeloperoxidase content is determined by the Advia 2120 hematology system by staining characteristics. Changes in myeloperoxidase staining are shown by location of neutrophils on Advia peroxidase dot plots and as myeloperoxidase index (MPXI). Significant changes in MPXI have been reported during severe inflammation in horses, dogs, and people but conclusions were inconsistent.
  
  
  OBJECTIVE
  Infusion of endotoxin was used to initiate an inflammatory stimulus under controlled conditions and over a longer time period than in previous studies to document kinetics of changes in neutrophil numbers, morphology, and myeloperoxidase staining. Identification of consistent time-related changes may allow better interpretation of changes in neutrophil characteristics during inflammation.
  
  
  METHODS
  Five Standardbred trotting horses received an intravenous infusion over a 6-hour period with Escherichia coli endotoxin. Neutrophil count, MPXI, neutrophil characteristics in Advia 2120 Perox dot plots and neutrophil morphology in blood smears were monitored with repeated sampling for up to 10 days.
  
  
  RESULTS
  Endotoxin infusion immediately caused severe neutropenia which converted to neutrophilia 14 hours after start of endotoxin infusion. Neutrophilia was still present 78 hours after start of infusion. Large "giant" neutrophils first appeared in blood smears and Advia Perox dot plots after 36-48 hours. A marked and consistent decrease in MPXI was seen in all horses 6 days (150 hours) after endotoxin exposure.
  
  
  CONCLUSIONS
  Endotoxemia caused prominent, time-related changes in equine neutrophil characteristics including emergence of giant neutrophils and markedly decreased MPXI several days after endotoxin infusion.
authors.affiliation: University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Inger
authors.initials: I
authors.lastname: Lilliehöök
authors.affiliation: University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.|Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Harold W
authors.initials: HW
authors.lastname: Tvedten
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Bröjer
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Edner
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Katarina
authors.initials: K
authors.lastname: Nostell
mesh_terms: D000818:Animals; D019446:Endotoxemia / Q000097:blood / Q000201:enzymology / Q000473:pathology*; D004731:Endotoxins / Q000009:adverse effects*; D006734:Horse Diseases / Q000097:blood / Q000201:enzymology / Q000473:pathology*; D006736:Horses; D007249:Inflammation / Q000662:veterinary; D009503:Neutropenia / Q000097:blood*; D009504:Neutrophils / Q000145:classification / Q000473:pathology*; D009195:Peroxidase / Q000097:blood*
chemical_list: D004731:Endotoxins; C044101:endotoxin, Escherichia coli; D009195:Peroxidase
keywords: Advia 2120; blood; giant neutrophils; horse; toxic changes