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 investigated as an adjunct to ristocetin-induced platelet aggregation (RIPA) studies because of problems experienced with aggregation studies, particularly at the time of presentation, in the pediatric age group. Eight patients suspected of having BSS were studied with respect to platelet 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 controls. One patient with Alport's syndrome, four patients with immune thrombocytopenic pul pura (ITP), and one patient with Glanzmann thrombasthenia were also studied. In all eight patients suspected of having BSS, deficiency of glycoprotein Ib alpha was demonstrated. Normal expression was demonstrated in 12 control patients, in one patient with giant platelets with Alport's syndrome, and in four patients with ITP. Absence of glycoprotein IIIa was demonstrated in Glanzmann thrombasthenia. In the pediatric age group one is able to demonstrate abnormalities of platelet membrane glycoprotien in patients with thrombocytopathias using flow cytometry. This method has the advantage of being rapid and can be performed on small volumes of blood suitable for pediatric practice.