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


CONCLUSIONS
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.
Department of Pediatrics, Medical University of Graz, Auenbruggerplatz 30, 8036 Graz, Austria. wolfgang.muntean@meduni-graz.at
A
A
Schlagenhauf
S
S
Schweintzger
R
R
Birner-Grünberger
B
B
Leschnik
W
W
Muntean
D000328:Adult; D001792:Blood Platelets / Q000378:metabolism / Q000502:physiology*; D005312:Fetal Blood / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D010743:Phospholipids / Q000097:blood; D010974:Platelet Aggregation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism*; D018179:Receptors, Thrombin / Q000378:metabolism*
D010743:Phospholipids; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D018179:Receptors, Thrombin