Patients with idiopathic, cyclic, and congenital neutropenia have recurrent severe bacterial infections. One hundred twenty-three patients with recurrent infections and severe chronic neutropenia (absolute neutrophil count < 0.5 x 10(9)/L) due to these diseases were enrolled in this multicenter phase III trial. They were randomized to either immediately beginning recombinant human granulocyte colony- stimulating factor (filgrastim) (3.45 to 11.50 micrograms/kg/d, subcutaneously) or entering a 4-month observation period followed by filgrastim administration. Blood neutrophil counts, bone marrow (BM) cell histology, and incidence and duration of infection-related events were monitored. Of the 123 patients enrolled, 120 received filgrastim. On therapy, 108 patients had a median absolute neutrophil count of = or = 1.5 x 10(9)/L. Examination of BM aspirates showed increased proportions of maturing neutrophils. Infection-related events were significantly decreased (P < .05) with approximately 50% reduction in the incidence and duration of infection-related events and almost 70% reduction in duration of antibiotic use. Asymptomatic splenic enlargement occurred frequently; adverse events frequently reported were bone pain, headache, and rash, which were generally mild and easily manageable. These data indicate that treatment of patients with severe chronic neutropenia with filgrastim results in a stimulation of BM production and maturation of neutrophils, an increase in circulating neutrophils, and a reduction in infection-related events.
Human neutrophils rapidly undergo apoptotic cell death. Because glucocorticoids are known to modulate an array of neutrophil functional activities as well as induce rapid apoptosis in susceptible lymphocyte populations, we have examined the effects of glucocorticoids on apoptosis in mature human neutrophils. In cultures of neutrophils maintained in vitro, the glucocorticoids, dexamethasone, 6 alpha-methylprednisolone, and hydrocortisone, inhibited the development of apoptotic morphology by 59% to 90% when assessed at 12, 24, and 48 hours. In contrast, corticosteroids lacking anti-inflammatory activity and progesterone failed to affect development of the morphologic features of apoptosis. The concentration of dexamethasone required to reduce apoptosis by 50% at 24 hours was approximately 5 x 10(-8) mol/L, a concentration that is achievable in plasma after dexamethasone treatment. Dexamethasone (10(-6) mol/L), but not progesterone, reduced the percentage of hypodiploid (apoptotic) nuclei by 40% to 90% over this time course. Similarly, dexamethasone reduced the DNA cleavage associated with apoptosis and prolonged the viability of neutrophils maintained in culture for 12 to 48 hours. Glucocorticoid-mediated modulation of neutrophil apoptosis was qualitatively similar, but lesser in magnitude, when compared with the effects of granulocyte colony-stimulating factor (100 ng/mL). Thus, glucocorticoids exert a protective effect on human neutrophil survival by delaying apoptosis.
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