Reduction of the inhibitory antibody response to human factor VIII in hemophilia A mice by mutagenesis of the A2 domain B-cell epitope

Blood. 2004 Aug 1;104(3):704-10. doi: 10.1182/blood-2003-11-3891. Epub 2004 Apr 8.

Abstract

Approximately 25% of patients with hemophilia A develop inhibitory antibodies after treatment with factor VIII. Most of the inhibitory activity is directed against epitopes in the A2 and C2 domains. Anti-A2 inhibitory antibodies recognize a 25-residue segment bounded by R484-I508. Several antigenic residues in this segment have been identified, including R484, R489, and P492. The immunogenicity of purified recombinant B domain-deleted (BDD) human factor VIII molecules containing mutations at R484A/R489A or R484A/R489A/P492A was studied in hemophilia A mice. Inhibitory antibody titers in mice receiving the R484A/R489A/P492A mutant, but not the R484A/R489A mutant, were significantly lower than in mice receiving control human BDD factor VIII. The specific coagulant activity and the in vivo clearance and hemostatic efficacy in hemophilia A mice of the R484A/R489A/P492A mutant were indistinguishable from human BDD factor VIII. Thus, the inhibitory antibody response to human factor VIII can be reduced by mutagenesis of a B-cell epitope without apparent loss of function, suggesting that this approach may be useful for developing a safer form of factor VIII in patients with hemophilia A.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Antibody Formation / genetics
  • B-Lymphocytes / immunology*
  • Blood Coagulation
  • Epitopes / genetics
  • Epitopes / immunology
  • Factor VIII / genetics*
  • Factor VIII / immunology*
  • Hemophilia A / blood
  • Hemophilia A / genetics*
  • Hemophilia A / immunology*
  • Humans
  • Mice
  • Mice, Transgenic
  • Molecular Sequence Data
  • Recombinant Proteins / immunology
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Swine

Substances

  • Epitopes
  • Recombinant Proteins
  • Factor VIII