Effects of lopap on human endothelial cells and platelets.
Severe consumption coagulopathy has been detected in rats after Lopap (a prothrombin activator from Lonomia obliqua caterpillar bristles) infusion and in humans after accidental contact with L. obliqua bristles. However, platelet count and antithrombin (AT) levels were only modestly affected, suggesting that a different form of blood coagulation activation may be involved in this hemorrhagic syndrome. Here we describe that Lopap had no effect on aggregation of washed human platelets induced by several agonists, suggesting that it might not impair platelet function in vivo. AT was able to inhibit the amidolytic activity of thrombin generated by incubation of Lopap with prothrombin in a purified system, which may be different from that generated by the prothrombinase complex in vivo. The surface expression of both ICAM-1 and E-selectin but not of VCAM-1 was upregulated by Lopap in cultured HUVEC, suggesting that it may behave differently from other mediators, such as thrombin and tumor necrosis factor-alpha.
Chudzinski-Tavassi
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Laboratory of Biochemistry and Biophysics, Center for Applied Toxinology, CEPID-FAPESP, Butantan Institute, Av. Vital Brazil 1500, 05503-900 São Paulo-SP, Brazil. amchudzinski@hotmail.com
Schattner
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Fritzen
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Reis
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Lourenço
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D000818:Animals; D001180:Arthropod Venoms / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects*; D015815:Cell Adhesion Molecules / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D007915:Lepidoptera; D010974:Platelet Aggregation / Q000187:drug effects; D011516:Prothrombin / Q000187:drug effects / Q000378:metabolism; D012697:Serine Endopeptidases / Q000494:pharmacology*; D014471:Umbilical Veins; D015854:Up-Regulation / Q000187:drug effects; D014841:von Willebrand Factor / Q000187:drug effects / Q000378:metabolism
D001180:Arthropod Venoms; D015815:Cell Adhesion Molecules; D014841:von Willebrand Factor; D011516:Prothrombin; C119835:Lonomia obliqua prothrombin activator protease; D012697:Serine Endopeptidases