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Factor VIII polypeptide specificity of monoclonal anti‐factor VIII antibodies
Author(s) -
Shima M.,
Yoshioka A.,
Nakai H.,
Tanaka I.,
Fujiwara T.,
Terada S.,
Imai S.,
Fukui H.
Publication year - 1988
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.1365-2141.1988.tb02435.x
Subject(s) - microbiology and biotechnology , monoclonal antibody , antibody , thrombin , chemistry , clotting factor , factor ix , factor x , factor vii , coagulation , biochemistry , biology , platelet , immunology , medicine
Four monoclonal antibodies against factor VIII, NMC‐VIII/1, NMC‐VIII/2, NMC‐VIII/3 and NMC‐VIII/4, were produced. The first three antibodies were of the IgG 1 immunoglobulin subclass, while the fourth was IgM. The affinity of each antibody for factor VIII was high and antifactor VIII clotting activity was detected in NMC‐VIII/2, NMC‐VIII/3 and NMC‐VIII/4. NMC‐VIII/1 had no inhibitory effect on factor VIII clotting activity. Immunoblotting using purified intact and thrombin‐treated factor VIII identified the antibodies’factor VIII polypeptide specificities. With thrombin‐treated factor VIII the factor VIII fragments for NMC‐VIII/1 and NMC‐VIII/2 were 80 kDa and 54 kDa, respectively, while both NMC‐VIII/3 and NMC‐VIII/4 recognised a 44 kDa fragment. With intact factor VIII, antibodies NMC‐VIII/2‐4 bound to polypeptides larger than 90 kDa, especially NMC‐VIII/2, which reacted with a chain of 330 kDa thought to be a mature form of factor VIII protein. We also detected a mature form of factor VIII in hepatic sinusoidal endothelial cells by immunoperoxidase staining. Identification of the factor VIII polypeptides bearing these fragments enabled us to clarify the localization of the factor VIII thrombin cleavage site, and suggested the existence of factor VIII in hepatic sinusoidal endothelial cells.