Characterization of an antibody to factor VIII in a patient with acquired hemophilia with circulating immune complexes

[Inhibitors of factor VIII in non-hemophilic patients. Biological and therapeutic aspects. Apropos of 3 cases]

A coagulation inhibitor of the anti-factor VIII: C type was detected in three non-haemophilic male patients aged 75, 70 and 52 respectively. In all three patients antibody titres were low (less than 12.5 Bethesda units initially, less than 20 units subsequently), and a low but detectable level of factor VIII: C persisted (7 to 12 p. 100 in two patients who had severe haemorrhages and 2.100 in the third one). The 3 inhibitors inactivated factor VIII: C with a complex, type II kinetics (Biggs et al.). Strong doses of anti-haemophilic A fractions were biologically effective in one patient but could not stop severe bleeding. Activated plasma fractions were used successfully on several occasions. Once, moderate and repeated doses of anti-haemophilic A fractions resulted in satisfactory correction of factor VIII: C level, and a minor surgical operation could be performed. An immunosuppressive treatment was administered for 3 weeks to one patient and for 3 months to the other two patients. In all three cases the inhibitor disappeared after 5 to 8 months. In non-haemophilic patients with factor VII: C inhibitor the treatment of haemorrhagic episodes must take into account the severity of bleeding, then the usually complex kinetics of the inhibitor; thus it cannot be a direct copy of the treatment used in haemophiliacs with type I inhibitors.