After 90 minutes' processing time, platelets obtained with the Amicus cell separator were significantly more activated than platelets harvested with the Spectra and the MCS+.

No abstract

The present results indicate an exhaustion of leukocyte ROS-generating mechanisms after prolonged strenuous exercise. This may partly explain the observation that athletes are more sensitive to attract infectious diseases if exposed to pathogenic micro-organisms during the immediate period after intensive physical activity.

Meningococcal-derived OMVs as well as purified meningococcal LPS, contribute to increased platelet-platelet and platelet-leukocyte aggregation and may thus be of great importance in the development of microthrombosis and organ dysfunction related to fulminant meningococcal septicemia.

We investigated the combined effect of wall shear rate and immobilized collagen on platelet activation in flowing nonanticoagulated human blood. By combining an ex vivo model of thrombogenesis with flow cytometry, we showed that activated platelets can be detected in the bloodstream passing growing thrombi at a wall shear rate characteristic of moderately stenosed arteries (2600 s-1). The activation of the circulating platelets was clearly correlated with thrombus growth. Different antibodies against platelet activation-dependent surface markers had distinct sensitivity to the thrombotic process. alpha-Granule release detected by surface expression of CD62P seemed to be the most sensitive marker, as judged by both mean fluorescence intensity and fraction of platelets activated. The conformational change in glycoprotein IIb-IIIa, as detected by PAC-1, also seemed to be a sensitive marker and preceded binding of fibrinogen to activated glycoprotein IIb-IIIa, as detected by anti-fibrinogen. Large thrombi also elicited lysosome exocytosis, detected by surface expression of CD63. Finally, we observed a small decrease of glycoprotein Ib-IX expression, as detected by anti-CD42a. Thus, our study provides further information on the dynamics of platelet activation in relation to thrombus growth at arterial shear conditions in flowing nonanticoagulated human blood.