A trial of recombinant human interleukin‐1 in patients with severe refractory aplastic anaemia

Summary. We report here the effects of in vivo administration of recombinant interleukin‐1 alpha (rIL‐1α) to patients with severe, idiopathic aplastic anaemia. Four patients who were refractory to immunosuppressive therapy and were not bone marrow transplantation candidates received daily doses of 0.03 μg/kg and 0.10 μg/kg intravenously as 5 d courses. No significant changes in either peripheral blood counts or bone marrow cellularity were observed at either dose during or following therapy. Two patients showed increased numbers of bone marrow progenitor colonies. Lymphocyte pheno typing demonstrated an elevated percentage of CD8 +/DR+ activated suppressor T lymphocytes prior to therapy. After rIL‐1α administration, the percentage of CD8 +/DR+ cells was reduced or returned to normal in all patients. Significant side‐effects included fever, rigours, fatigue, headache and nausea. Transient hypotension was observed at both doses in all patients. These results suggest that while rIL‐1α can be safely administered, no significant haematologic improvement was observed in patients with severe aplastic anaemia.