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Activation of human platelets through gp140, the C3d/EBV receptor (CR2)

1987; Wiley; Volume: 17; Issue: 4 Linguagem: Inglês

10.1002/eji.1830170413

1521-4141

Danièle Nunez, Christiane Charriaut‐Marlangue, Monique Barel, Jacques Benveniste, Raymond Frade,

Monoclonal and Polyclonal Antibodies Research

Abstract gp140, the C3d/EBV receptor (CR2), previously isolated and characterized from human B lymphocytes, was identified on human platelets: (a) by measuring the specific binding of either polyclonal anti‐gp140 IgG and monoclonal anti‐C3d/EBVR antibodies, as OKB‐7 and HB‐5, or human C3d; (b) by isolating gp140 from solubilized platelet components with polyclonal anti‐gp140 IgG or monoclonal OKB‐7, using immunoprecipitation and electro‐immunoblotting assays; (c) by inducing specific activation of human platelets. Cross‐linking of this receptor by polyclonal anti‐gp140 IgG induced aggregation of human platelets and stimulated ATP release. Absence of lactate dehydrogenase release and inhibition by EDTA and prostacyclin of anti‐gp140‐induced aggregation, support strongly active aggregation and absence of lysis. Platelet aggregation by anti‐gp140 required metabolic activities and was modulated by fibrinogen, paf‐acether or thrombin. OKB‐7 triggered human platelet aggregation when cross‐linked by anti‐mouse second‐step antibodies. In the same way, platelet activation by C3d fragment was detected, in presence of fibrinogen, only when C3d was cross‐linked on the cell surface by anti‐C3d F(ab′) 2 fragments.