High incidence of anti‐FVIII antibodies against non‐coagulant epitopes in haemophilia A patients: a possible role for the half‐life of transfused FVIII

The occurrence of antibodies (Abs) capable of inhibiting factor VIII (FVIII) coagulant activity is a severe complication in haemophilia A, leading to the inhibition of transfused FVIII activity. It is not known whether, or to what extent, post‐transfusion antibodies may also arise against non‐coagulant epitopes. Therefore we set up a system capable, in theory, to detect all the FVIII‐induced antibodies by use of an enzyme‐linked immunoassorbent assay (ELISA) based on coating human recombinant FVIII onto polystyrene microtitre plates. Serum samples from 23 patients affected by haemophilia A of different gravity (22 referred to our Centre and one to the Bari Centre) were analysed. Although only one patient was positive at Bethesda assay, the presence of antibodies in ELISA was detected in 39% of patients in variable degrees; transfusion with FVIII was found to induce a raise in antibody titre, arguing in favour of the specificity of the phenomenon. The clinical relevance of these non‐inhibitory antibodies was evaluated in three patients; although half‐life did not show any change in the patients without or with low amount of antibodies, FVIII clearance was found enhanced in the patient displaying high titre antibodies. We propose detection of anti‐FVIII antibodies by ELISA when routinely assessing haemophilia A patients.

[1]  L. Hoyer.  WHY DO SO MANY HAEMOPHILIA A PATIENTS DEVELOP AN INHIBITOR? , 1995, British journal of haematology.

[2]  S. Antonarakis,et al.  Molecular etiology of factor VIII deficiency in hemophilia A , 1995, Human mutation.

[3]  J. Saint-Remy,et al.  Healthy subjects produce both anti-factor VIII and specific anti-idiotypic antibodies. , 1994, The Journal of clinical investigation.

[4]  E G Tuddenham,et al.  Haemophilia A: database of nucleotide substitutions, deletions, insertions and rearrangements of the factor VIII gene, second edition. , 1994, Nucleic acids research.

[5]  M. Baiget,et al.  Inversions in the factor VIII gene in Spanish hemophilia A patients. , 1994, Blood.

[6]  W. Kreuz,et al.  Screening of F.VIII:C Antibodies by an Enzyme‐Linked Immunosorbent Assay , 1994, Vox sanguinis.

[7]  V. Regnault,et al.  Quantitation of factor VIII antibodies by an enzyme-linked immunoassay method. , 1994, Blood.

[8]  Stylianos E. Antonarakis,et al.  Inversions disrupting the factor VIII gene are a common cause of severe haemophilia A , 1993, Nature Genetics.

[9]  J. Arnout,et al.  Anti-factor VIII antibodies of hemophiliac patients are frequently directed towards nonfunctional determinants and do not exhibit isotypic restriction. , 1993, Blood.

[10]  I. Scharrer,et al.  Incidence of inhibitors in haemophiliacs. A review of the literature. , 1993, Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis.

[11]  T. Schumacher,et al.  Polymorphisms in pockets of major histocompatibility complex class I molecules influence peptide preference , 1993, The Journal of experimental medicine.

[12]  D. Lakich,et al.  Sequence of the murine factor VIII cDNA. , 1993, Genomics.

[13]  A. Miller,et al.  Dominance and crypticity of T cell antigenic determinants. , 1993, Annual review of immunology.

[14]  J. Ware,et al.  Epitope mapping of human factor VIII inhibitor antibodies by site‐directed mutagenesis of a factor VIII polypeptide , 1992, Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis.

[15]  P. Green,et al.  Factor VIII gene explains all cases of haemophilia A , 1992, The Lancet.

[16]  M. Kazatchkine,et al.  Natural antibodies to factor VIII (anti-hemophilic factor) in healthy individuals. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[17]  E G Tuddenham,et al.  Haemophilia A: database of nucleotide substitutions, deletions, insertions and rearrangements of the factor VIII gene, second edition. , 1994, Nucleic acids research.

[18]  J. Aznar,et al.  Immunological characterization of factor VIII inhibitors by a sensitive micro-ELISA method. , 1990, Thrombosis research.

[19]  R. Houghten,et al.  A murine monoclonal anti-factor VIII inhibitory antibody and two human factor VIII inhibitors bind to different areas within a twenty amino acid segment of the acidic region of factor VIII heavy chain. , 1990, Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis.

[20]  J. Ware,et al.  Identification of a F.VIII epitope recognized by a human hemophilic inhibitor. , 1989, Blood.

[21]  C. Fulcher,et al.  Epitope mapping of human factor VIII inhibitor antibodies by deletion analysis of factor VIII fragments expressed in Escherichia coli. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[22]  D. Green,et al.  A More Uniform Measurement of Factor VIII Inhibitors , 1975, Thrombosis and Haemostasis.