Engineered FVIII-expressing cytotoxic T cells target and kill FVIII-specific B cells in vitro and in vivo

Blood Adv. 2018 Sep 25;2(18):2332-2340. doi: 10.1182/bloodadvances.2018018556.


Hemophilia A is an X-linked bleeding disorder caused by mutations in the factor VIII (FVIII) gene (F8). Treatment with recombinant or plasma-derived FVIII replacement therapy is standard therapy. A major problem in treating hemophilia A patients with therapeutic FVIII is that 20% to 30% of these patients produce neutralizing anti-FVIII antibodies (inhibitors) because they are not immunologically tolerant to this human protein. Hence, there is a need to establish tolerogenic protocols to FVIII epitopes. To specifically target FVIII-specific B cells, we engineered immunodominant FVIII domains (A2 and C2) as a chimeric antigen receptor expressed by both human and murine cytotoxic T cells. This FVIII domain engineered B-cell antibody receptor (BAR) that expresses T cells was capable of killing FVIII-reactive B-cell hybridomas in vitro and in vivo. Moreover, FVIII BAR CD8 T cells blocked the development of specific antibody from unimmunized spleen cells stimulated polyclonally with lipopolysaccharide in vitro. In addition, adoptive transfer of FVIII A2- and C2-BAR CD8 T cells significantly reduced the anti-FVIII antibody formation in hemophilic mice. These data suggest that BAR-engineered T cells are a promising approach for future prophylactic treatment for patients with severe hemophilia A who are at high risk of developing inhibitors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / metabolism*
  • CD8-Positive T-Lymphocytes
  • Cytotoxicity, Immunologic*
  • Factor VIII / genetics*
  • Factor VIII / immunology
  • Gene Expression*
  • Hemophilia A / genetics
  • Hemophilia A / immunology
  • Humans
  • Lymphocyte Activation / immunology
  • Mice
  • Mice, Knockout
  • T-Lymphocytes, Cytotoxic / immunology*
  • T-Lymphocytes, Cytotoxic / metabolism*


  • Factor VIII