CONTINUOUS-INFUSION OF FACTOR-IX CONCENTRATE TO INDUCE IMMUNE TOLERANCE IN 2 PATIENTS WITH HEMOPHILIA-B

Two patients with haemophilia B and high-responding inhibitor to facto r IX were subjected to immune tolerance induction according to the Mal mo protocol, including high dosage of factor IX, cyclophosphamide and intravenous gammaglobulin. In one of the patients the treatment was pr eceded by extracorporeal protein A adsorption. Both patients had previ ously been subjected to immune tolerance induction without success and as an attempt to improve the tolerance induction regimen and lower co st, factor IX was given as continuous infusion, with a dose of around 300 units per kg body weight daily for 3 weeks. The inhibitor level de clined in one of the patients but tolerance was not achieved. In the s econd patient the inhibitor level remained high. Despite the failure o f the treatment in these two cases, we propose that the constant antig en load provided by the continuous infusion of modern, safe, purified factor IX concentrate may theoretically be of greater benefit in immun e tolerance induction than the varying load resulting from intermitten t infusions. Larger study materials are needed to show if this is so.