Abstract
Whole blood flow cytometry, an important new method for the assessment of platelet
function, is particularly advantageous for neonatal studies because only minuscule
volumes (∼2 μL) of blood are required. By this method, we have demonstrated that neonatal
platelets are less reactive than adult platelets to physiological agonists in whole
blood, as determined by the activation-induced increase in the platelet surface expression
of P-selectin and the glycoprotein (GP) Ilb-IIIa complex and by the activation-induced
decrease in the platelet surface expression of the GPIb-IX complex. Our data suggest
that the mechanism of neonatal platelet hyporeactivity is, at least in part, a relative
defect in a common signal transduction pathway. We have further demonstrated that
the platelets of very low birth weight (VLBW) preterm neonates are maximally hyporeactive
on days 3 to 4 of life but return to almost the adult range by days 10 to 14. Given
that intraventricular hemorrhage (IVH) is also maximal on days 3 to 4, these defects
may contribute to the propensity of VLBW preterm neonates to IVH.
Keywords:
Newborn - platelets - P-selectin - GPIIb-IIIa - flow cytometry
