We present results concerning the pathogenic mechanism of heparin-induced thrombocytopenia type I. An ELISA was developed for directly measuring the expression of glycoprotein IIb/IIIa (GPIIb/IIIa) on platelets in the presence and absence of ADP and under the influence of various heparins. In addition, the release of ADP and platelet factor 4 (PF4) was measured in platelet-rich plasma. Heparin also induced the expression of GPIIb/IIIa without prior stimulation with ADP. On the other hand we could demonstrate that the addition of heparins and protamine sulfate to platelets resulted in a significant release of intracellularly stored ADP and PF4. These results suggested that heparin(oid)s modulate the expression of GPIIb/IIIa with ADP as a mediator, and that protamine sulfate is contraindicated as an antidote in heparin-induced thrombocytopenia.

Adenosine Diphosphate↗

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[Test Limulus, Its interest (author's transl)].

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