Eosinophil response to SCH55700 in patients with HES. Absolute eosinophil count (closed symbols) as a function of time is shown prior to and following a single 1 mg/kg dose of SCH55700 (A-B). Absolute eosinophil counts prior to and following multiple-dose SCH55700 (1 mg/kg intravenously unless otherwise noted) are shown in panels C (patient 1) and D (patient 2). Arrows indicate drug administration. Serum levels of SCH55700 are represented by open symbols (D).