One patient who received cyclophosphamide had hematuria that was related to the inhibitor, not to cyclophosphamide cystitis. Another patient receiving cyclophosphamide developed reversible dysplastic changes in bone marrow after 104 weeks. One patient had an anaphylactoid reaction to porcine factor VIII, and one patient had an anaphylactoid reaction to activated prothrombinase complex concentrate. Discussion Acquired autoantibodies to coagulation factors are uncommon. This figure may be an underestimate because symptoms can vary and spontaneous remissions can occur in persons with low titers of inhibitors.
Autoantibodies usually occur with no identifiable cause.
Anti-factor VIII antibodies can occur in conjunction with other autoimmune diseases, especially rheumatoid arthritis, lupus erythematosus, and inflammatory bowel disease. A transient and usually mild form of factor VIII inhibitors is seen in postpartum women. Successful treatment of factor VIII inhibitors requires immediate control of hemorrhage and long-term suppression of the autoantibody. If patients have inhibitor levels greater than 5 Bethesda units or do not respond adequately to human factor VIII, then porcine factor VIII, activated prothrombinase complex concentrates, or recombinant factor VIIa are necessary. Activated coagulation factors should be used initially if the titer of antiporcine antibodies is high or unknown , but repeated doses should be given judiciously because of the risk for thrombosis.