Rapid and sustained remission of systemic juvenile idiopathic arthritis-associated macrophage activation syndrome through treatment with anakinra and corticosteroids.

We describe 2 patients with systemic juvenile idiopathic arthritis and macrophage activation syndrome. Treatment with recombinant interleukin 1 receptor antagonist (anakinra) and a corticosteroid rapidly induced remission, which could be maintained with anakinra monotherapy at a stable dose of 2 mg/kg per day. Pain at the injection site during the initial injections was the only adverse effect attributable to anakinra. Untoward effects of corticosteroid treatment were mild because prolonged therapy with high-dose corticosteroids could be avoided. These results suggest that early institution of interleukin 1 blockade merits further investigation for the treatment of macrophage activation syndrome and, perhaps, related conditions such as hemophagocytic lymphohistiocytosis.