Bronchial Epithelial Cell-derived Cytokines (G-CSF and GM-CSF Promote the Survical of Peripheral Blood Neutrophils In Vitro

Abstract

Neutrophil accumulation in the respiratory tract occurs in a variety of inflammatory disorders, particularly those associated with cigarette smoking. We examined whether bronchial epithelial cells could contribute to this accumulation through the production of factors that increased the survival of neutrophils. Pure primary cultures of human bronchial epithelial cells (HBEC) were used to generate conditioned medium (CM), and the effect of this CM on the survival of neutrophils in vitro was examined. When neutrophils were cultured in control medium, survival was 8.7 ± 1.7% at 72 h. In contrast, culture of neutrophils in CM resulted in a dose-dependent increase in survival: 22.6 ± 5.5, 43.6 ± 4.2, and 64 ± 3.8% in 1, 10, and 50% CM respectively (mean ± SEM; P < 0.05). As evidenced by the examination of neutrophil DNA, this prolongation of survival was associated with suppression of apoptosis. Cytokines with known actions on neutrophil biology identified in the CM included granulocyte colony-stimulating fact...