Characterization of an in vitro platelet function analyzer, PFA-100(TM)

A new in vitro system for the evaluation of platelet function, PFA-100 (currently under evaluation) is characterized. The system monitors platelet aggregation on a collagen-epinephrine-coated membrane as whole blood sample is aspirated under controlled flow conditions through a microscopic aperture cut into the membrane, The time required for the platelet plug to occlude the aperture (closure time) is indicative of the platelet function in the sample. Incubation of normal blood samples with antibodies to glycoprotein (GP) Ib, GPIIb-IIIa, von Willebrand factor, or with the peptide Arg-Gly-Asp-Ser, resulted in a concentration-dependent prolongation in closure time. An anti-fibrinogen antibody did not impact the closure time. Closure time was also prolonged when the hematocrit or the platelet count was lowered to pathological values. The study indicates that PFA-100 could detect defects in platelet adhesion or aggregation. The simplicity of the test makes PFA-100 unique for rapid screening of a variety of platelet dysfunction.