A B S T R A C T Previous reports have described conflicting results concerning the glycoprotein (GP) and protein composition of Bernard-Soulier platelets. In view of this controversy we have analyzed the platelets of four Bernard-Soulier patients using improved single and two-dimensional sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis procedures. An absence of staining for carbohydrate of membrane GP lb was characteristic for the platelets of each patient. Major periodate-Schiff staining bands corresponding to membrane GP lIb, Illa, and IlIb were clearly detected and their presence was confirmed by two-dimensional SDS-polyacrylamide gel electrophoresis. The protein content of the Bernard-Soulier platelets was increased two-to fourfold. However, analysis of their protein composition using 7-12% acrylamide gradient gels showed normal polypeptide profiles. Lactoperoxidase-catalyzed 125I-labeling of the Bernard-Soulier platelet surface proteins was followed by SDS-polyacrylamide gel electrophoresis and autoradiography. No labeling in the Ib position was detected whereas the other major membrane GP, including Ia and Ila, were normally located. In contrast, GP lb was clearly detected by periodate-Schiff staining and autoradiography when normal human platelets that had been exhaustively treated with neuraminidase before the lactoperoxidase-catalyzed iodination were analysed. No abnormalities were detected in the GP patterns of membranes isolated from the patients' erythrocytes. Only a severe molecular abnormality or possible deletion of GP lb could account for this major platelet lesion in the Bernard-Soulier syndrome.

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The Tn-syndrome is an acquired disorder characterized by the polyagglutination of blood cells and the pathological exposure of a-N-acetyl-D-galactosamine residues (Tn-antigen) at the cell surface. We now report studies on the platelets of a patient (Ba.) of which 81% reacted positively with a fluorescein conjugate of Helix pomatia agglutinin (HPA). The surface proteins of Ba. platelets were labeled with 125I by the lactoperoxidase-catalyzed procedure; single and twodimensional electrophoresis on sodium dodecyl sulfate (SDS)-polyacrylamide gels was followed by autoradiography that revealed normal '251-labeling of the major membrane glycoproteins (GP) but that GP lb had a faster than normal migration. The abnormal GP lb of Ba. platelets was strongly labeled when platelet suspensions were treated sequentially with neuraminidase, galactose oxidase, and sodium [3H]borohydride. Unlike the GP Ib of normal human platelets, it was also strongly labeled when Ba. platelets were treated with galactose oxidase and sodium [3H]borohydride alone. Both the alloantigen, PHAl, and quinidine-dependent antibody receptor activity were normally expressed by Ba. platelets, which also bound a monoclonal antibody (AN51) to GP lb. Analysis of Ba. platelets by crossed immunoelectrophoresis using a rabbit anti-human platelet antibody preparation revealed the presence of an immunoprecipitate in the GP lb position that had an abnormal appearance and migration in the second dimension. An altered position of the precipitate given by Factor VIIIR:Ag was also noted. Incorporation of HPA into the agarose gel during the first dimension electrophoresis resulted in the specific precipitation of the abnormal GP lb of Ba. platelets.Address reprint requests to Dr. Nurden, H6pital Lari-boisiere.