Background: Platelets contain a complex known as GPIb-IX-V. The receptorfor vWF is located in GPIba. The number of functional receptors decreases during thrombin activationof platelets. This study was performed to evaluate the percentage of platelets displaying the GPIbalpha-IX complex on their surface Material/Methods: We studied 51 healthy term newborns (21 females and 30males). Blood was collected from the umbilical artery and vein immediately after severance of the umbilicalcord, using a Diatube TM CTAD Vacutainer System. The GPIbalpha-IX complex was tested with CD42b-PE antibody,using a EPICS XL flow cytometer. Results: Practically no differences were observed in the percentageof platelets demonstrating CD42b in venous blood (18.59%) and arterial blood (19.37%). The percentageof platelets bearing the CD42b molecule is higher in male newborns (20.58%) than female (17.38%). Healthycontrol adults demonstrated an increased percentage of CD42b on platelets (30.4%) in comparison to newborns(18.98%). Conclusions: The sex of neonates affects the tested complex: higher values were noted in males.The particular umbilical vessel (vein or artery) has no effect on the percentage of platelets bearingCD42b.

Keywords: Blood Platelets - metabolism, Fetal Blood - cytology, Infant, Newborn, Platelet Glycoprotein GPIb-IX Complex - metabolism, Platelet Membrane Glycoproteins - metabolism, Receptors, Cell Surface - metabolism, Sex Factors