Relapse pattern and long-term outcomes in subjects with acquired haemophilia A.

INTRODUCTION: Acquired haemophilia A (AHA) is a rare autoimmune bleeding disorder caused by neutralizing antibodies against factor VIII (FVIII). Despite significant initial morbidity and mortality, most patients achieve remission with immunosuppressive therapy. AIM: Long-term follow-up data from the Quebec Reference Centre for Inhibitors (QRCI) were analysed to identify factors predictive of AHA relapse and the influence of relapse on survival. METHODS: Criteria used to define AHA were levels of FVIII <0.3 IU/mL and FVIII inhibitor titres ≥0.6 Bethesda Units (BU). Complete remission was defined as FVIII >0.5 IU/mL and/or FVIII inhibitor titres <0.6 BU while not on immunosuppression. RESULTS: Between 2000 and 2012, 111 subjects met the inclusion criteria and were followed for a median of 25.6 months. Ninety per cent of them reached remission on immunosuppression in a median time of 45 days. Fourteen patients presented one or more relapses in a median time of 13.4 months. Most relapse episodes were successfully treated. Associated lymphoproliferative syndromes (LPS) were predictive of relapse, whereas FVIII activity and inhibitor titres at initial diagnosis or immunosuppressive regimens were not. The overall survival (OS) was the same, with or without relapse. CONCLUSION: Among the recognized potential risk factors for relapse, only LPS was statistically significant. The long-term follow-up of our patients also showed that late or multiple relapses may occur, but that relapse is not associated with a worse OS. Thus, long-term follow-up is important for optimal management of AHA.

Characterization of anti-factor VIII antibody in a patient with acquired hemophilia A.

Acquired hemophilia A (AHA) is a bleeding disorder caused by the development of an auto-antibody against endogenous factor VIII (FVIII). In this study, the epitope of the autoantibody was identified in a 67-year-old female patient with AHA. A prolonged activated partial thromboplastin time (77.4 s) that failed to correct in an incubation mixing test (68.2 s), a decreased FVIII activity, and a high FVIII inhibitor (14.6 Bethesda units/mL) were observed. Enzyme-linked immunosorbent assay demonstrated that the antibody belonged to the immunoglobulin G4 subclass. An immunoblotting assay revealed the light chain (A3/C1/C2 domain) of FVIII as the binding region of the antibody. The bleeding experienced by our patient resulted from the interference of FVIII binding to both FIX by anti-A3 antibodies and phospholipids and von Willebrand factor by anti-C2 antibodies. To the best of our knowledge, this is the first study in Korea characterizing an autoantibody in the context of AHA.

Characterization of anti-factor VIII antibody in a patient with acquired hemophilia A

Acquired hemophilia A (AHA) is a bleeding disorder caused by the development of an auto-antibody against endogenous factor VIII (FVIII). In this study, the epitope of the autoantibody was identified in a 67-year-old female patient with AHA. A prolonged activated partial thromboplastin time (77.4 s) that failed to correct in an incubation mixing test (68.2 s), a decreased FVIII activity, and a high FVIII inhibitor (14.6 Bethesda units/mL) were observed. Enzyme-linked immunosorbent assay demonstrated that the antibody belonged to the immunoglobulin G4 subclass. An immunoblotting assay revealed the light chain (A3/C1/C2 domain) of FVIII as the binding region of the antibody. The bleeding experienced by our patient resulted from the interference of FVIII binding to both FIX by anti-A3 antibodies and phospholipids and von Willebrand factor by anti-C2 antibodies. To the best of our knowledge, this is the first study in Korea characterizing an autoantibody in the context of AHA.

Characterization of anti-factor VIII antibody in a patient with acquired hemophilia A

Acquired hemophilia A (AHA) is a bleeding disorder caused by the development of an auto-antibody against endogenous factor VIII (FVIII). In this study, the epitope of the autoantibody was identified in a 67-year-old female patient with AHA. A prolonged activated partial thromboplastin time (77.4 s) that failed to correct in an incubation mixing test (68.2 s), a decreased FVIII activity, and a high FVIII inhibitor (14.6 Bethesda units/mL) were observed. Enzyme-linked immunosorbent assay demonstrated that the antibody belonged to the immunoglobulin G4 subclass. An immunoblotting assay revealed the light chain (A3/C1/C2 domain) of FVIII as the binding region of the antibody. The bleeding experienced by our patient resulted from the interference of FVIII binding to both FIX by anti-A3 antibodies and phospholipids and von Willebrand factor by anti-C2 antibodies. To the best of our knowledge, this is the first study in Korea characterizing an autoantibody in the context of AHA.