Marked Eosinophilia Induced by Recombinant Human Interleukin-2

Abstract

A 79-year-old man developed a red tumor measuring about 2cm in diameter on his left lower leg. A biopsy specimen showed typical features of angiosarcoma. Magnetic resonance imaging revealed five additional tumors in his left thigh muscles. We resected the tumor in the lower leg and performed radiotherapy for the intramuscular tumors on his thigh. In addition, we started the intravenous infusion of recombinant human interleukin-2 (rIL-2) at a daily dose of 400,000U. Ten days later the dosage was doubled. Twenty-five days after the start of treatment with rIL-2, the eosinophil counts increased to 68% (9452/μl) of the WBC counts. The serum IL-5 level was 15.6pg/ml, and the eosinophil cationic protein (ECP) was 77.2μg/l: which both exceeded the upper limits of normal variation. The serum IL-4 level was within the normal range. After the cessation of rIL-2, the eosinophil counts, IL-5 and ECP returned to the normal level. The IgE values remained unchanged. These findings suggest that the eosinophilia during rIL-2 therapy was associated with an elevation in the serum IL-5 level, while rIL-2 did not induce the IL-5-producing-cells to produce IL-4.