title: Induction of Mycobacterium tuberculosis-specific primary and secondary T-cell responses in interleukin-15-deficient mice.
abstract: Several studies have provided evidence that interleukin-15 (IL-15) can enhance protective immune responses against Mycobacterium tuberculosis infection. However, the effects of IL-15 deficiency on the functionality of M. tuberculosis-specific CD4 and CD8 T cells are unknown. In this study, we investigated the generation and maintenance of effector and memory T-cell responses following M. tuberculosis infection of IL-15(-/-) mice. IL-15(-/-) mice had slightly higher bacterial numbers during chronic infection, which were accompanied by an increase in gamma interferon (IFN-gamma)-producing CD4 and CD8 T cells. There was no evidence of increased apoptosis or a defect in proliferation of CD8 effector T cells following M. tuberculosis infection. The induction of cytotoxic and IFN-gamma CD8 T-cell responses was normal in the absence of IL-15 signaling. The infiltration of CD4 and CD8 T cells into the lungs of "immune" IL-15(-/-) mice was delayed in response to M. tuberculosis challenge. These findings demonstrate that efficient effector CD4 and CD8 T cells can be developed following M. tuberculosis infection in the absence of IL-15 but that recall T-cell responses may be impaired.
authors.affiliation: Department of Molecular Genetics and Biochemistry, W1157 Biomedical Science Tower, University of Pittsburgh School of Medicine, 200 Lothrop Street, Pittsburgh, PA 15261, USA.
authors.forename: Vanja
authors.initials: V
authors.lastname: Lazarevic
authors.forename: David J
authors.initials: DJ
authors.lastname: Yankura
authors.forename: Sherrie J
authors.initials: SJ
authors.lastname: DiVito
authors.forename: JoAnne L
authors.initials: JL
authors.lastname: Flynn
mesh_terms: D000818:Animals; D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D019409:Interleukin-15 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008168:Lung / Q000276:immunology / Q000382:microbiology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000472:pathogenicity; D014397:Tuberculosis, Pulmonary / Q000276:immunology* / Q000382:microbiology / Q000503:physiopathology
chemical_list: D019409:Interleukin-15; D007371:Interferon-gamma