Merck

Inhibition of human platelet aggregation by eosinophils.

Life sciences (2013-07-23)
Aline Mendes Maziero, Raquel Lorenzetti, José Luiz Donato, Sergio Lilla, Gilberto De Nucci
ABSTRACT

The relationship between the activity of eosinophils and platelets has been observed in recent decades by many scientists. These observations include increased numbers of eosinophils associated with platelet disorders, including changes in the coagulation cascade and platelet aggregation. Based on these observations, the interaction between eosinophils and platelets in platelet aggregation was analyze. Human platelets were incubated with eosinophil cytosolic fraction, promyelocytic human HL-60 clone 15 cell lineage, and eosinophil cationic protein (ECP). Platelet rich plasma (PRP) aggregation was induced by adenosine diphosphate, platelet activating factor, arachidonic acid, and collagen, and washed platelets (WP) were activated by thrombin. Aggregation induced by all agonists was dose dependently inhibited by eosinophil cytosolic fraction. This inhibition was only partially reversed by previous incubation of the eosinophils with l-Nitro-Arginine-Methyl-Ester (l-NAME). Previous incubation with indomethacin did not prevent the cytosolic fraction induced inhibition. The separation of eosinophil cytosolic fraction by gel filtration on Sephadex G-75 showed that the inhibitory activity was concentrated in the lower molecular weight fraction. HL-60 clone 15 cells differentiated into eosinophils for 5 and 7 day were able to inhibit platelet aggregation. The ECP protein inhibited the platelet aggregation on PRP and WP. This inhibition was more evident in WP, and the citotoxicity MTT assay proved the viability of tested platelets, showing that the observed inhibition by the ECP protein does not occur simply by cell death. Our results indicate that eosinophils play a fundamental role in platelet aggregation inhibition.

MATERIALS
Product Number
Brand
Product Description

Supelco
Sephadex® G-50, Medium
Sigma-Aldrich
Sephadex® G-50, Superfine
Sigma-Aldrich
Sephadex® G-50, Fine
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Arachidonic acid, >95.0% (GC)
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Arachidonic acid, from non-animal source, ≥98.5% (GC)
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Sephadex® G-50, BioReagent, for molecular biology, DNA grade, fine
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Arachidonic acid sodium salt, from Porcine liver, ≥99% (capillary GC), waxy solid
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Sephadex® G-50, BioReagent, for molecular biology, DNA grade, medium
Supelco
Dextran, analytical standard, for GPC, 270,000
Supelco
Dextran, analytical standard, for GPC, 670,000
Supelco
Dextran, analytical standard, for GPC, 150,000
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Dextran, analytical standard, for GPC, 80,000
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Dextran, analytical standard, for GPC, 410,000
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Dextran from Leuconostoc spp., Mr 15,000-25,000
Supelco
Dextran, analytical standard, for GPC, 5,000
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Dextran from Leuconostoc spp., Mr ~40,000
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Dextran from Leuconostoc spp., Mr ~2,000,000
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Sephadex® G-25, Fine
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Sephadex® G-15, Medium
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Sephadex® G-100, Superfine
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Sephadex® G-100, Medium
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Sephadex® G-75, Medium
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Sephadex® G-25, Medium
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Sephadex® G-25, Coarse
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Sephadex® G-75, Superfine
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Dextran from Leuconostoc spp., Mr ~6,000
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