FLOW CYTOMETRIC ANALYSIS OF PLATELET SURFACE GLYCOPROTEINS IN THE DIAGNOSIS OF BERNARD-SOULIER SYNDROME

The use of flow cytometry in the diagnosis of Bernard-Soulier syndrome (BSS) in patients with giant platelets and thrombocytopenia was inves tigated as an adjunct to ristocetin-induced platelet aggregation (RIPA ) studies because of problems experienced with aggregation studies, pa rticularly at the time of presentation, in the pediatric age group. Ei ght patients suspected of having BSS were studied with respect to plat elet expression of glycoprotein Ib alpha (CD42b) and glycoprotein IIIa (CD61) using an EPICS Profile II flow cytometer. Twelve patients with normal platelet morphology and platelet counts were used as normal co ntrols. One patient with Alport's syndrome, four patients with immune thrombocytopenic pul pura (ITP), and one patient with Glanzmann thromb asthenia were also studied. In all eight patients suspected of having BSS, deficiency of glycoprotein Ib alpha was demonstrated. Normal expr ession was demonstrated in 12 control patients, in one patient with gi ant platelets with Alport's syndrome, and in four patients with ITP. A bsence of glycoprotein IIIa was demonstrated in Glanzmann thrombasthen ia. In the pediatric age group one is able to demonstrate abnormalitie s of platelet membrane glycoprotien in patients with thrombocytopathia s using flow cytometry. This method has the advantage of being rapid a nd can be performed on small volumes of blood suitable for pediatric p ractice.