Activated platelets and platelet-leukocyte aggregates in the equine systemic inflammatory response syndrome

Abstract

In humans, activated platelets contribute to sepsis complications and to multiple organ failure. In our prospective analytical study of cases of the equine systemic inflammatory response syndrome (SIRS), we adapted a standard human protocol for the measurement of activated platelets and platelet-leukocyte aggregates (PLAs) in equine platelet-leukocyte-rich plasma (PLRP) by flow cytometry, and we investigated the hypothesis that activated platelets and PLAs are increased in clinical cases of SIRS. We included 17 adult horses and ponies fulfilling at least 2 SIRS criteria, and 10 healthy equids as controls. Activation of platelets was determined by increased expression of CD62P on platelets. Activated platelets and PLAs were measured before and after in vitro activation of platelets with collagen. Median expression of CD62P on platelets was significantly increased after activation in the control group: 1.45% (interquartile range [IQR]: 1.08–1.99%) initially versus 8.78% (IQR: 6.79–14.78%, p = 0.002) after activation. The equids with SIRS had significantly more activated platelets and PLAs in native PLRP than controls: CD62P 4.92% (median, IQR: 2.21–12.41%) versus 1.45% in controls (median, IQR: 1.08–1.99%, p = 0.0007), and PLAs 4.16% (median, IQR: 2.50–8.58%) versus 2.95% in controls (median, IQR: 1.57–3.22%, p = 0.048). To our knowledge, increased platelet activation and PLAs have not been demonstrated previously with flow cytometry in clinical cases of equine SIRS.

Biomarkers of in vivo platelet activation in thoroughbreds during their first long-term training

“…Flow cytometry is considered the gold standard method for the study of EVs, allowing the accurate identification and enumeration of EV subpopulations based on the use of distinct monoclonal antibodies that detect cell-specific surface proteins in both humans and horses ( 1 , 36 , 37 ). In this study, we applied a standardized flow cytometry protocol for the identification and enumeration of EVs in equine plasma using an anti-CD61 antibody, as previously reported ( 24 ).…”