title: IL-9 regulates pathology during primary and memory responses to respiratory syncytial virus infection.
abstract: IL-9 is a cytokine of great current interest associated with allergic/Th2 responses. High levels of IL-9 are present in bronchial secretions from infants with respiratory syncytial virus (RSV) bronchiolitis. To test its effects in RSV disease with a Th2 profile, BALB/c mice were vaccinated with recombinant vaccinia virus expressing the RSV G protein. On RSV challenge, immunized mice developed augmented disease characterized by enhanced pulmonary Th2 and local IL-9 production peaking on days 7-10 of RSV infection. Depletion with anti-IL-9 Ab at vaccination or RSV challenge enhanced viral clearance. Depletion only at challenge had no effect on disease severity, whereas depletion at immunization and challenge enhanced Th1 responses, inhibited virus-specific IgG1 production, and enhanced disease severity. By contrast, depletion of IL-9 at immunization boosted IgG2a and inhibited the Th2 response and disease during subsequent infection without a concomitant increase in type 1 cytokines. Adoptive transfer of secondary memory CD4 T cells from the spleens of IL-9-depleted mice into naive recipients replicated many of the effects of depletion, indicating that IL-9 acts via CD4 T cells. Therefore, IL-9 is a previously unknown but key modulator of antiviral immunity, regulating T and B cell responses and having potent and specific effects on viral lung disease.
authors.affiliation: Department of Respiratory Medicine, St. Mary's Campus, Imperial College, London W2 1PG, United Kingdom.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Dodd
authors.forename: Eda
authors.initials: E
authors.lastname: Lum
authors.forename: John
authors.initials: J
authors.lastname: Goulding
authors.forename: Roshell
authors.initials: R
authors.lastname: Muir
authors.forename: Jacques
authors.initials: J
authors.lastname: Van Snick
authors.forename: Peter J M
authors.initials: PJ
authors.lastname: Openshaw
mesh_terms: D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007156:Immunologic Memory; D016906:Interleukin-9 / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology / Q000473:pathology*; D012136:Respiratory Syncytial Viruses / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology* / Q000821:virology; D018418:Th2 Cells / Q000276:immunology* / Q000821:virology
chemical_list: D007074:Immunoglobulin G; D016906:Interleukin-9