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A monoclonal antibody directed against a granule membrane glycoprotein (GMP‐140/PADGEM, P‐selectin, CD62P) inhibits ristocetin‐induced platelet aggregation
Author(s) -
BOUKERCHE HABIB,
RUCHAUDSPARAGANO MARIEHéLèNE,
R OUEN CHRISTINE,
BROCH IER JEAN,
KAPLAN CéCILE,
MCGREGOR JOHN LOUIS
Publication year - 1996
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.1996.d01-1485.x
Subject(s) - platelet , ristocetin , monoclonal antibody , platelet membrane glycoprotein , chemistry , thrombin , microbiology and biotechnology , von willebrand factor , p selectin , platelet glycoprotein gpib ix complex , platelet activation , glycoprotein , glycoprotein ib , affinity chromatography , thrombasthenia , antibody , biochemistry , immunology , biology , platelet aggregation , enzyme
P‐selectin (also called CD62, GMP‐140, PADGEM, CD62P) is a recently described member of a family of vascular adhesion receptors expressed by activated platelets and endothelial cells that are involved in leucocyte cell adhesion. The aim of this study was to characterize a new monoclonal antibody (LYP7) directed against activated human blood platelets that inhibits ristocetin‐induced platelet aggregation. Immunoadsorbent affinity chromatography and immunoprecipitation studies showed that LYP7 (IgG 1 ) bound a surface‐labelled glycoprotein (GP) which changed its apparent molecular mass (M r ) on reduction from 138 kD (situated below GPIIb) to 148 kD (above GPIIbα). LYP7 and S12, a monoclonal antibody directed against P‐selectin immunoprecipitated the same band. Using ELISA assay, purified P‐selectin was shown to bind LYP7 and S12 monoclonal antibodies. Binding sites of 125 I‐labelled LYP7, which was greatly increased on thrombin‐stimulated (2 U/ml) washed platelets (10825±2886, mean ±SD) ( K d =1.5±0.5 n m ) compared to resting platelets (2801±1278, mean ±SD) ( K d =1.5±0.6 n m ), was found to be normal on thrombin‐stimulated platelets taken from a patient with grey platelet syndrome or a patient with Glanzmann thrombasthenia. LYP7 (IgG 1 , F(ab′) 2 or Fab fragments) inhibited ristocetin‐induced platelet aggregation of platelets in a dose‐dependent fashion without affecting the binding of von Willebrand (vWf ) factor. However, agglutination of formaldehyde‐fixed platelets induced by ristocetin was not affected by monoclonal antibody LYP7. In addition, the binding of thrombin‐activated platelets to neutrophils was inhibited by monoclonal antibody LYP7. These results strongly suggest that P‐selectin, by promoting cell–cell contact, may play an active role in platelet–platelet interactions.