Il-8 Induced Chemotaxis of Peripheral Neutrophils in Children with Cystic Fibrosis (Cf)

Abstract

Inflammation associated with neutrophil infiltration is a commonly observed feature of children with CF. Production of the major neutrophil chemotactic cytokine interleukin-8 (IL-8) by alveolar macrophages or supporting cells is potentially of great importance in the pathology of CF. We have previously shown that both sputum and BAL IL-8 concentrations are higher in children with CF compared with asthmatics, normal children or children with lung infection. We have therefore investigated the chemotactic effects of IL-8 on peripheral neutrophils obtained from a CF group (n=18, aged 4–20 yr) and a control group of normal children (n=13, aged 5–12 yr). Cells were isolated by dextran sedimentation followed by separation on Lymphoprep. Chemotaxis was assayed using multiwell microchemotaxis chambers and 5.tm polycarbonate filters. Filters were fixed and stained with Haema-Gurr for counting. Results are expressed as number of neutrophils per high power field (HPF). Optimal chemotaxis of control and CF neutrophils were observed at an IL-8 concentration of 1x10^-8M. At the optimum concentration the numberof cells migrating were 150 ± 11/HPF for controls and 140 ± 14/HPF for the CF group (p=n.s.). At lower IL-8 concentrations, the number of neutrophils migrating were significantly lower for the CF group (p=0.042 at 1x10^-9M and p=0.026 at 5x10^-9M). These results show that neutrophils from both control and CF groups have receptors for IL-8, but that the CF group have a different degree of responsiveness to this cytokine. The mechanism underlying this is currently under investigation.