RESPIRATORY SYNCYTIAL VIRUS-INDUCED CYTOKINE PRODUCTION BY A HUMAN BRONCHIAL EPITHELIAL-CELL LINE

Respiratory syncytial virus (RSV) is the most common cause of lower re spiratory infection in infants and young children, but the pathogenesi s of RSV-induced inflammation is not well defined. We hypothesized tha t in vitro infection of a human bronchial epithelial cell line (BEAS) would induce production of proinflammatory cytokines. BEAS cells were infected with RSV, and cells and supernatants were assayed for cytokin e mRNA and protein changes at several time points after infection. Cyt okine mRNA in BEAS cells was measured by polymerase chain reaction of reverse-transcribed RNA from whole cell lysates; cytokine levels in su pernatants were measured by bioassay or immunoassay. Our results indic ated that interleukin-8 (IL-8) was induced at 4 h after infection (dur ing the eclipse phase of RSV infection) with accumulation of IL-8 in s upernatants by 24 h after infection. Increased levels of IL-6 and gran ulocyte macrophage colony-stimulating factor in supernatants were only detected by 96 h after infection, during the RSV replicative phase. I nterferon-alpha and -gamma transcripts were not detectable at any time point. We conclude that the effects of RSV on airway inflammation may be at least partly mediated by sequential production of proinflammato ry cytokines in infected airway epithelium.