Inflammatory mediators in dengue virus infection in children: Interleukin-8 and its relationship to neutrophil degranulation

The chemokine interleukin-8 (IL-8) has chemoattractant activity for neutrop hils and is able to activate and degranulate these cells, We investigated w hether IL-8 may exert these effects in children with dengue virus infection . Circulating levels of IL-8, neutrophilic elastase (a constituent of the a zurophilic granule of neutrophils), and lactoferrin, released from specific granula, were measured in 186 children with dengue virus infection, 33 hea lthy children as negative controls and 11 children with bacterial infection s as positive controls. Levels of IL-8 on admission were elevated in 71% of the dengue patients, while the elastase and lactoferrin Levels were increa sed in 68 and 17% of patients, respectively. These levels were significantl y higher than in healthy children (P < 0.05) for IL-8 and elastase but not for lactoferrin (by the Wilcoxon-Mann-Whitney [WMW] U test). Similar levels of IL-8 were found in patients with bacterial infections. Levels of IL-8 a nd elastase in patients with shock were significantly higher than in patien ts without shock (P = 0.02; WMW), but those of lactoferrin were not. IL-8 c orrelated with elastase and lactoferrin (r = 0.19 and P = 0.009 versus r = 0.24 and P = 0.001, respectively; two-tailed Spearman rank correlation). Th us, IL-8 levels are increased in most patients with dengue virus infection and correlate with degranulation of neutrophils as well as with some clinic al and hemodynamic variables. These findings suggest a role for IL-8 in the pathogenesis of dengue virus infection.