Neutrophils in induced sputum from healthy children: Role of interleukin-8 and oxidative stress

Summary Background It is unclear why the neutrophil differential count in induced sputum (IS) from normal children is highly variable. Since levels of neutrophil chemoattractant cytokines and oxidative stress are determinants of airway neutrophilia in animal models, we sought to determine the association between IS neutrophils from healthy children and (i) interleukin-8 (IL-8) and (ii) the oxidative stress marker 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG). Methods IS was done using hypertonic saline. The proportion (differential %) and the absolute number of IS neutrophils were determined by light microscopy. IS IL-8 and 8-oxodG were determined using ELISA. Spearman's rank correlation (Rs) was used to assess relationship between variables. Results Adequate IS samples for analysis were obtained from 64/114 healthy children. The median (interquartile range) neutrophil differential count ( n =64) was 20.6% (5.67–56), and absolute neutrophil count ( n =53) was 0.11×106 (0.01–0.77). Both the % neutrophils, and the absolute neutrophil count were associated with IL-8 (Rs=0.67, p