Interferon therapy of idiopathic thrombocytopenic purpura]

The authors evaluated the efficacy of a daily administration of recombinant human alpha 2a interferon (IFN), given at a dose of 300MU for 12 consecutive days, in patients with steroid-nonresponsive or -dependent idiopathic thrombocytopenic purpura (ITP). Nine patients received courses of IFN therapy. Mean platelet counts rose from 1.39 to 10.9 x 10(4)/microliters and PAIgG decreased from 151.7 to 59.7 ng/10(7) cells. The maximum rise in platelet counts occurred from 10 to 42 days (mean 19.1) after the initiation of IFN. Complete response (CR) was achieved in 3 of 13 courses (23.1%), and partial response (PR) in 8 (61.5%). One CR case continued for longer than 20 months without further treatment, but intermittent IFN therapy was necessary for the other. The increment of the platelet counts was transient in all of the partial responders. No severe side effect requiring interruption of the course of IFN was experienced. Both serum IgG and PAIgG significantly correlated with the increment of platelet counts, therefore the mechanism of IFN on ITP was presumed to be associated with the inhibition of autoantibody production. Daily administration of IFN appears to be an effective and safe treatment protocol for refractory ITP.