Identifying human platelet glycoproteins IIb and IIIa by capillary electrophoresis

Glanzmann thrombasthenia (GT) is an inherited hemorrhagic defect due to a failure of the platelet membrane glycoprotein (GP) IIb-IIIa complex. Capillary electrophoresis (CE) analysis of solubilized platelet membranes from normal individuals showed the presence of two peaks with a migration time of 27 and 29 min, respectively. An excellent run-to-run and day-to-day reproducibility of the technique (< 1% variation of the retention time) was documented. Using an automated Ferguson method, the apparent molecular masses were 100.0 kDa and 138.5 kDa, respectively. Immunoprecipitation with monoclonal antibodies anti-GP IIIa (B59.2.1) and anti-IIb (61.9.1.3) showed the two peaks as IIIa and IIb, respectively. Electropherograms of a GT young man showed the lack of both peaks. Less than 50% of each peak was present in his parents. Polyacrylamide gel electrophoresis (PAGE), immunoblotting, and flow cytometry analyses showed that GP IIb and IIIa were undetectable in the platelet membranes from the propositus, half of the normal amount being present in both parents. These findings indicate CE to be a rapid, sensitive and reliable tool to investigate patients with abnormalities of the GP IIb-IIIa complex.