THE EFFECT OF A SINGLE COURSE OF INTERFERON-ALPHA-2B IN PATIENTS WITHHIV-RELATED AND CHRONIC IDIOPATHIC IMMUNE THROMBOCYTOPENIA

13 patients with HIV-related immune thrombocytopenia (HIV-ITP) and 10 patients with chronic idiopathic thrombocytopenic purpura (C-ITP) were treated with a single course of alpha-2b-Interferon (IFN 3 x 10(6) IU subcutaneously for 12 d). The patients had platelet counts lower than 40 x 10(9)/L and thrombocytopenia persisting for over 1 year (range 1 -22 years); 7 patients were refractory to previous conventional therap y, 5 were responsive, and 11 had not been previously treated. The resp onse to IFN was complete in 8 patients (platelets >100 x 10(9)/L), par tial in 7 (platelets 50-100 x 10(9)/L); 8 patients showed no response. The treatment with IFN was stopped after 4 d in one patient due to a fall in platelet count. The maximal platelet count (median peak 116 +/ - 55 SD X 10(9)/L platelets) was obtained after 13.7 +/- 2.98 d and th e improvement in platelet count was maintained for 22.8 +/- 8.6 d. No difference in platelets response was observed between HIV-ITP and C-IT P. The response to IFN seems to be related to the one obtained with pr evious treatments. Indeed 80% of the patients who were responsive to p revious steroids, high dose immunoglobulins or azidothymidine (HIV-ITP ) showed a complete or partial response while only 43% of the refracto ry patients showed a partial response; the positive response rate in p reviously untreated patients was 73%.