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A monoclonal antibody (B724) to von Willebrand factor recognizing an epitope within the Al disulphide loop (Cys509‐Cys695) discriminates between type 2A and type 2B von Willebrand disease
Author(s) -
CHRISTOPHE O.,
ROUAULT C.,
OBERT B.,
PIETU G.,
MEYER D.,
GIRMA J. P.
Publication year - 1995
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 - 10.1111/j.1365-2141.1995.tb03400.x
Subject(s) - ristocetin , von willebrand factor , polyclonal antibodies , monoclonal antibody , platelet , epitope , chemistry , von willebrand disease , microbiology and biotechnology , antibody , recombinant dna , platelet membrane glycoprotein , platelet glycoprotein gpib ix complex , platelet adhesiveness , biochemistry , immunology , glycoprotein , medicine , biology , platelet aggregation , gene
Monoclonal antibody (MoAb) B724 to von Willebrand factor (vWF) completely inhibits its interaction with heparin, sulphatides and botrocetin and consequently botrocetin‐induced binding of vWF to platelets. MoAb B724 has no effect on the binding of vWF to collagen or to ristocetin‐treated platelets nor on vWF‐dependent platelet aggregation induced with ristocetin and asialo‐vWF‐mediated platelet aggregation. MoAb B724 preferentially recognizes a conformation of native vWF, in solution, or immobilized through a coated antibody. It exhibits a markedly lower affinity for vWF immobilized onto collagen or plastic surfaces. Using proteolytic fragments of vWF, B724 epitope was localized within the 512–673 sequence of the Al disulphide loop of vWF, MoAb B724 was used as second antibody in a two‐site ELISA to test a series of patients with type 1, 2 A, 2B and 2N vWD or haemophilia A and recombinant wild type or mutated vWFs. Results were compared with those obtained by control ELISAs performed using polyclonal antibodies. Using MoAb B724, strikingly lower levels of vWFAg were observed in plasma from most patients with type 2B vWD, and in seven out of the eight rvWF mutated close to or within the Al disulphide loop. Therefore MoAb B724, which interferes with this loop involved in the function of vWF, appears to be a useful tool for rapid screening of conformational changes in this region.