title: IL-12-independent Th1-type immune responses to respiratory viral infection: requirement of IL-18 for IFN-gamma release in the lung but not for the differentiation of viral-reactive Th1-type lymphocytes.
abstract: We demonstrated that IL-12 was induced during primary or secondary pulmonary adenoviral infection in wild-type (wt) mice. However, cellular responses were not compromised in the lungs of IL-12-/- mice. The level of IFN-gamma in the lung was similar in wt and IL-12-/- mice during pulmonary viral infection. Upon Ag stimulation in vitro, lymphocytes from draining lymph nodes or spleen of infected IL-12-/- mice released large amounts of IFN-gamma, but not IL-4, which were comparable to those released by wt lymphocytes. Furthermore, a predominantly IgG2a response to adenoviral infection was unimpaired in IL-12-/- mice. These significant anti-adenoviral Th1-type responses in IL-12-/- mice led to an efficient clearance of virus-infected cells in the lung. Whether IL-18 was involved in IL-12-independent anti-adenoviral immune responses was investigated. Abrogation of endogenous IL-18 by an Ab resulted in diminished IFN-gamma release and lymphocytic infiltrate in the lung during adenoviral infection. Nevertheless, the development of lymphocytes of the Th1 phenotype was unimpaired in the absence of both IL-12 and IL-18. In contrast to their intact ability to mount Th1-type responses to viral infection, IL-12-/- mice suffered impaired Th1-type immune responses to pulmonary mycobacterial infection. Our findings suggest that IL-12, although induced, is not required for Th1-type responses to respiratory viral infection, in contrast to mycobacterial infection. IL-18 is required for the optimal release of IFN-gamma in the lung during viral infection, but is not required for the generation of virus-reactive Th1-type lymphocytes. Th1 differentiation during respiratory adenoviral infection may involve molecules different from IL-12 or IL-18.
authors.affiliation: Department of Pathology and Molecular Medicine and Division of Infectious Diseases, Centre for Gene Therapeutics, McMaster University, Hamilton, Ontario, Canada. xingz@fhs.csu.mcmaster.ca
authors.forename: Z
authors.initials: Z
authors.lastname: Xing
authors.forename: A
authors.initials: A
authors.lastname: Zganiacz
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Divangahi
authors.forename: F
authors.initials: F
authors.lastname: Nawaz
mesh_terms: D000257:Adenoviridae Infections / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D000260:Adenoviruses, Human / Q000276:immunology; D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D002454:Cell Differentiation / Q000276:immunology; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000378:metabolism*; D018664:Interleukin-12 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D020382:Interleukin-18 / Q000502:physiology*; D008168:Lung / Q000276:immunology* / Q000378:metabolism; D008171:Lung Diseases / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008198:Lymph Nodes / Q000276:immunology; D016676:Macrophages, Alveolar / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009163:Mycobacterium bovis / Q000276:immunology; D013154:Spleen / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology* / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D019076:Transgenes / Q000276:immunology; D014397:Tuberculosis, Pulmonary / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; C515456:CCL11 protein, human; C515457:Ccl11 protein, mouse; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016207:Cytokines; D020382:Interleukin-18; D018664:Interleukin-12; D007371:Interferon-gamma