Comparative evaluation of PAR1, GPIb-IX-V, and integrin αIIbβ3 levels in cord and adult platelets

Summary

Background: Newborn platelets show hyposensitivity in vitro to many important agonists. However, sensitivity of platelets to these agonists is crucial for a functional clot formation. Nevertheless newborns have an excellent hemostasis. Hence, we examined levels of PAR1 thrombin receptor, GPIb-IX-V (CD42b), and Integrin αIIbβ3 in newborn and adult platelets using Western blot analysis.Materials, methods: Platelets of adult and cord blood were isolated, washed, and lysed. Protein samples were separated by SDS-PAGE and blotted on nitrocellulose membranes. Receptors were visualized using immunodetection and evaluated densitometrically. Statistical analysis was performed using SPSS 16.0. Results: We found significantly lower levels of PAR1-receptors and higher levels of CD42b in newborn platelets as compared to adult platelets. Levels of Integrin αIIbβ3 in newborn platelets were comparable to adult platelets. Conclusion: A lower content of PAR1-receptors explains very well the hyposensitivity of cord platelets to thrombin. Higher levels of CD42b may additionally support the effect of larger more adhesive multimeric vWF in newborn plasma.

Zusammenfassung

Hintergrund: Neugeborenen-Thrombozyten weisen in vitro eine Hyposensitivität gegenüber wichtigen Agonisten auf, deren Reaktivität jedoch notwendig ist für eine funktionierende Hämostase. Dennoch haben Neugeborene keine Blutungsneigung. Daher untersuchten wir mittels Western-Blots Neugeborenen- und Erwachsenen-Thrombozyten auf deren Gehalt an PAR1-Thrombinrezeptoren, GPIb-IX-V (CD42b) und Integrin αIIbβ3. Material, Methoden: Thrombozyten von Erwachsenen- und Nabelschnurblut wurden isoliert, gewaschen und lysiert. Die Proteinproben wurden mittels SDS-PAGE aufgetrennt, auf Nitrozellulose-Membranen geblottet, und die Rezeptoren mittels Immunodetektion sichtbar gemacht. Die Banden wurden densitometrisch ausgewertet. Statistische Analysen wurden mit SPSS 16.0 durchgeführt. Ergebnisse: Ein signifikant niedrigerer Gehalt an PAR1-Rezeptoren und ein signifikant höherer Gehalt an CD42b in Neugeborenen-Thrombozyten konnte festgestellt werden. Der Gehalt von Integrin αIIbβ3 war vergleichbar mit Erwachsenen. Schlussfolgerung: Eine geringere Menge an PAR1-Rezeptoren liefert eine gute Erklärung für die Hyposensitivität von Neugeborenen-Thrombozyten gegenüber Thrombin.

Keywords

Newborn haemostasis - platelet receptors - Western blot - thrombin receptor

Schlüsselwörter

Neugeborenen-Hämostase - Thrombozytenrezeptoren - Western Blot - Thrombinrezeptor

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