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Procoagulant microparticles in dogs with immune-mediated hemolytic anemia
L Kidd1, J Geddings2, Y Hisada2
1Western University of Health Sciences College of Veterinary Medicine, Pomona, CA.
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.
Hypothesis/Objectives:
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.
Animals:
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 And Clinical Importance:
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.
