A PROSPECTIVE-STUDY OF TREATMENT OF ACQUIRED (AUTOIMMUNE) FACTOR-VIIIINHIBITORS WITH HIGH-DOSE INTRAVENOUS GAMMA-GLOBULIN

A decrease in inhibitor titer has been reported in some patients with acquired factor VIII inhibitors treated with intravenous gammaglobulin (IGIV). We have conducted a prospective, multicenter study of high-do se IGIV in treatment of this disorder to determine efficacy. Nineteen patients received induction therapy with IGIV, 1,000 mg/kg x2 consecut ive days or 400 mg/kg x5 consecutive days, followed by maintenance dos es at intervals as clinically indicated. A greater than or equal to 25 % reduction in inhibitor titer was observed in 8 of 16 assessable pati ents, six of whom met the criteria for response. A rapid decline in in hibitor titer over 3 to 4 days was observed in two patients, but in fo ur additional responding patients-two of whom received repetitive main tenance doses of IGIV-the decline was more gradual, with final nadirs being reached several weeks to many months after treatment. The inhibi tor disappeared in three patients with low-level inhibitors, less than 1 Bethesda unit (BU). Concomitant therapy with prednisone may have co ntributed to the response in two of the patients but was not a factor in four patients; the response rate is, therefore, estimated to be bet ween 25% and 37.5%. These results confirm the beneficial effect of IGI V in treatment of some patients with acquired autoimmune factor VIII i nhibitors. (C) 1995 by The American Society of Hematology.