STUDY OBJECTIVE: To define the clinical and hematologic effects of recombinant 
human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on patients 
with chronic severe neutropenia.
DESIGN: Open-label, phase II study of rhGM-CSF.
SETTING: Inpatient hematology and surgery clinic at a university medical center.
PATIENTS: Four consecutive patients with chronic severe neutropenia, which in 
two cases was complicated by severe infection, in one case by perianal fistula, 
and in one case by complete rectal prolapse. Two patients had chronic idiopathic 
neutropenia; one patient had congenital neutropenia (myelokathexis); and one 
patient had autoimmune neutropenia.
INTERVENTIONS: The rhGM-CSF was given intravenously or subcutaneously at 
starting dosages of 150 to 1000 micrograms/m2 body surface area.d for 12 to 14 
consecutive days. Two patients received a second course of daily rhGM-CSF 
treatment after a nontreatment interval of 14 to 20 days.
MEASUREMENTS AND MAIN RESULTS: In all four patients, the absolute neutrophil 
counts increased from less than 0.25 x 10(9)/L to 3.2 to 19.2 x 10(9)/L within 2 
weeks of beginning rhGM-CSF therapy. Two patients had life-threatening 
infections that resolved during therapy. The two other patients had major 
ano-rectal surgery during rhGM-CSF treatment and had no postoperative 
infections.
CONCLUSIONS: In patients with chronic neutropenia, rhGM-CSF may increase 
neutrophil counts. This therapy may be a useful adjunct to antibiotic therapy 
for patients with infection and perioperatively for patients having anorectal 
surgery.