Cytokine levels during symptomatic viral upper respiratory tract infection

Background: Previous studies suggest a role for locally produced proinflammatory cytokines in the development and expression of illness during experimental infection with a variety of respiratory viruses. However, most of these studies fail to make comparisons between symptomatic and asymptomatic infected subjects. Objective: To compare the pattern of nasal cytokine elaboration in asymptornatic and symptomatic subjects experimentally infected with rhinovirus-39 (RV-39). Methods: Healthy adults underwent experimental intranasal inoculation with a safety-tested clinical isolate of RV-39. Nasal lavages were collected, nasal symptoms were recorded, and expelled nasal secretions were weighed before and then daily for 6 days after challenge. Nasal lavages were submitted for viral culture and assayed for cytokine protein levels by enzyme-linked immunosorbent assay. Results: Twenty-nine subjects were enrolled in the study. All subjects were infected as evidenced by viral shedding and/or seroconversion. Sixteen subjects were symptomatic and 13 were asymptornatic as evaluated by subject self-report. During infection, significant increases in mean levels of nasal interleukin 6 (IL-6) (P = .01) and IL-1 (P = .02) were observed in symptomatic but not asymptomatic subjects. In symptomatic subjects, these increases were temporally related to the development of nasal symptoms and production of secretions. Mean levels of IL-8, IL40, and tumor necrosis factor a were not increased in either group during infection. Conclusions: The results of this study demonstrate elevations in certain locally produced cytokines during symptomatic but not asymptornatic respiratory infection with RV-39. Future studies using selected anticytokine therapies may help elucidate the precise role of cytokines in mediating disease expression.