Interleukin-8 (IL-8) is a major cytokine in the recruitment of neutrophils (polymorphonuclear leukocytes) to areas of inflammation. It also activates T lymphocytes and cytokine-primed basophils and eosinophils and therefore may be implicated as an effector in allergic inflammation. IL-8 has also been identified as a mediator in such inflammatory pulmonary conditions as cystic fibrosis, allergen challenge, and sarcoidosis. To investigate the bioactivity of IL-8 in humans, we examined the effects of nasal challenge with human recombinant IL-8 in a double-blind placebo-controlled crossover study in which nasal resistance and rhinitic symptoms were monitored for 4 h after challenge. Cellular infiltration was quantified on differentially stained nasal smears obtained at hourly intervals. Cellular responses caused by in vivo priming were assessed by a comparison of atopic and nonatopic patient groups. A significant neutrophilic infiltrate in smear samples was observed in all patients challenged with IL-8 from 12 +/- 4% (mean +/- SEM) at baseline to 60 +/- 6% after 4 h; placebo challenge resulted in an increase in neutrophils to 30 +/- 4% (p < 0.04). Additionally, a significant increase in cumulative eosinophil recruitment occurred over the challenge period. Nasal resistance was significantly increased 10 min after instillation of IL-8 in all subjects compared with placebo, but there was no difference between atopic and nonatopic subjects. Nasal rhinitic symptoms were also increased in all subjects receiving IL-8 compared with placebo. In a further study in 19 subjects, nasal biopsy was performed 3 h after IL-8 or placebo challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

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