PurposeRecombinant human granulocyte-macrophage colony stimulating factor (GM-CSF) was administered to two patients with glycogen storage disease, type lb (GSD-lb), with chronic neutropenia, neutrophil dysfunction, and recurrent infections in an effort to increase neutrophil counts and increase resistance to infections.Patients and MethodsThe patients' baseline absolute neutrophil counts (ANC) ranged from 56 to 480 cells/mm3despite increased granulocyte precursors in the bone marrow. GM-CSF was given s.c. at starting doses of 500 μg/m2/day divided into two doses.ResultsAfter 48 h, ANC rose to 2,025 cells/mm3and 3,132 cells/mm3, respectively. Absolute eosinophil counts also rose to 1,048 cells/mm3(24%) and 4,820 cells/mm3(33%) on days 10 and 9 in the two patients. Although an initial 10-day course of GM-CSF was tolerated in one patient without significant reactions, subsequent s.c. injections of GM-CSF were complicated by increasingly painful local reactions that necessitated discontinuation after 7 to 8 days. Intravenous infusion was associated with a febrile systemic reaction. Despite lack of improvement in neutrophil superoxide anion generation measured in one, both patients demonstrated unusually rapid healing of cutaneous infections on GM-CSF.ConclusionOur experience suggests that GM-CSF may be useful for short-term treatment of serious infections in GSD-lb. However, alternate dosage schedules or different preparations of GM-CSF to diminish local reactions would be required for long-term maintenance therapy. Granulocyte colony stimulating factor (G-CSF) has also been shown to increase neutrophils in this disease and has not been associated with allergic reactions.