title: Procoagulant microparticles in dogs with immune-mediated hemolytic anemia.
abstract: BACKGROUND
  Studies of some human prothrombotic diseases suggest that phosphatidylserine-positive (PS+) and tissue factor-positive (TF+) microparticles (MPs) might play a role in the pathogenesis of thrombosis or serve as biomarkers of thrombotic risk.
  
  
  OBJECTIVE
  To determine if circulating levels of PS+MP and procoagulant activity (PCA) associated with PS+MPs and TF+ MPs are increased in dogs with IMHA.
  
  
  METHODS
  Fifteen dogs with primary or secondary IMHA and 17 clinically healthy dogs.
  
  
  METHODS
  Prospective case-controlled observational study. Circulating PS+MPs were measured by flow cytometry. PCA associated with PS+MPs and TF+MPs was measured by thrombin and Factor Xa generating assays, respectively.
  
  
  RESULTS
  Circulating numbers of PS+MPs were not significantly higher in dogs with IMHA [control median 251,000/μL (36,992-1,141,250/μL); IMHA median 361,990/μL (21,766-47,650,600/μL) P = .30]. However, PS+MP PCA [control median 2.2 (0.0-16.8) nM PS eq; IMHA median 8.596, (0-49.33 nM PS eq) P = .01] and TF+MP PCA [control median 0.0, (0.0-0.0 pg/mL); IMHA median 0.0; (0-22.34 pg/mL], P = .04) were increased. Intravascular hemolysis, which we showed might increase PS+ and TF+MP PCA, was evident in 3 of 5 dogs with PS+MP PCA and 2 of 4 dogs with TF+MP PCA higher than controls. Underlying disease in addition to IMHA was detected in 1 of 5 dogs with PS+PCA and 3 of 4 dogs with TF+MP PCA higher than controls.
  
  
  CONCLUSIONS
  TF+ and PS+MP PCA is increased in some dogs with IMHA. Further studies that determine if measuring TF+ and PS+ MP PCA can help identify dogs at risk for thrombosis are warranted.
authors: Western University of Health Sciences College of Veterinary Medicine, Pomona, CA.
authors: L
authors: L
authors: Kidd
authors: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors: J
authors: J
authors: Geddings
authors: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors: Y
authors: Y
authors: Hisada
authors: California Veterinary Specialists, Ontario, CA.
authors: M
authors: M
authors: Sueda
authors: California Veterinary Specialists, Ontario, CA.
authors: T
authors: T
authors: Concannon
authors: Francis Owen Blood Research Laboratory Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors: T
authors: T
authors: Nichols
authors: Francis Owen Blood Research Laboratory Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors: E
authors: E
authors: Merricks
authors: Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors: N
authors: N
authors: Mackman
mesh_terms: D000744:Anemia, Hemolytic, Autoimmune / Q000188:drug therapy / Q000662:veterinary*; D000818:Animals; D001780:Blood Coagulation Tests / Q000662:veterinary; D016022:Case-Control Studies; D003029:Coagulants / Q000008:administration & dosage / Q000627:therapeutic use*; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D005260:Female; D005434:Flow Cytometry; D006400:Hematocrit / Q000662:veterinary; D008297:Male; D061212:Memory, Episodic; D008863:Microspheres
chemical_list: D003029:Coagulants
keywords: Auto-immune hemolytic anemia; Hemolysis; Microvesicle; Phosphatidylserine; Procoagulant; Tissue factor