Interaction between target cell CD47 and the inhibitory macrophage receptor signal regulatory protein (SIRP ) counteracts macrophage phagocytosis of CD47expressing host cells. As platelets also express CD47, we asked whether inhibitory CD47/SIRP signaling regulates normal platelet turnover and clearance of platelets in immune thrombocytopenic purpura (ITP). CD47 / mice had a mild spontaneous th...

Interspecies platelet immunizations among marmosets lead to antibody formation to the donor platelets and a profound thrombocytopenia, which when associated with anemia may result in death of the animal. This actively induced immunologic thrombocytopenia closely resembles two clinical disease entities manifesting autoimmune thrombocytopenia, posttransfusion purpura and idiopathic thrombocytopen...

The effectiveness of different methods of leukoreduction in preventing alloimmune platelet refractoriness was evaluated in a canine model. Platelets from a random donor dog were administered for up to 8 weeks or until platelet refractoriness. Standard (STD; unmodified) platelets were accepted by 14% of recipients (n 7) compared with 14% for centrifuge leukoreduced (C-LR) platelets (n 21) and 31...

Alzheimer's disease (AD) is characterized by extracellular beta-amyloid plaques and intracellular tau tangles. AD-related pathology is often accompanied by vascular changes. The predominant vascular lesions in AD are cerebral amyloid angiopathy (CAA) and arteriosclerosis. Platelets circulate along the vessel wall responding immediately to vascular injury. The aim of the present study was to exp...

Monocytes are thought to play a role in host resistance to tumor cell growth in animals and humans. In addition, platelets are known to be involved in tumor metastases. To investigate the interaction of these two cell types and their effect on tumor cells, human monocytes and platelets were examined using an in vitro monocyte-tumor cell cytotoxicity assay. Monocytes alone resulted in 32% +/- 1....

After exposure to an agonist, platelets are activated and become aggregated. They also shed membrane microparticles that participate in the pathogenesis of thrombosis, hyper-coagulation and inflammation. However, microvesiculation can potentially disrupt the integrity of platelet aggregation by shedding the membrane receptors and phosphatidylserine critical for forming and stabilising a platele...

After the intravenous infusion of N-hydroxysuccinimido biotin into dogs, 80.6% +/- 9.7% (n = 5) of platelets were covalently labeled with biotin. The in vivo survival of the biotinylated platelets was monitored by flow cytometry and was normal as compared with previous reports for dog platelets. The ability of the biotinylated platelets to be activated was analyzed by measuring the expression o...

OBJECTIVE Reduced antiplatelet drug efficacy occurs in conditions of increased platelet turnover, associated with increased proportions of drug-free, that is, uninhibited, platelets. Here, we detail mechanisms by which drug-free platelets promote platelet aggregation in the face of standard antiplatelet therapy. APPROACH AND RESULTS To model standard antiplatelet therapy, platelets were treat...