Leukemia is the most common type of cancer in children, with an annual incidence of about 5 per 100,000 children in the United States. Up to 20–30% of patients with acute leukemia develop hyperleukocytosis, placing them at risk for life-threatening complications.

Although definitive treatment for acute leukemia involves chemotherapy, leukapheresis—to urgently reduce dangerously elevated white blood cell counts—is a potentially life-saving therapeutic option. During leukapheresis, a large machine uses centrifugation to separate white blood cells, or leukocytes, from the rest of the blood, which is then returned to the patient.