title: Interleukin-7 or interleukin-15 enhances survival of Mycobacterium tuberculosis-infected mice.
abstract: Both antigen-presenting cells and immune effector cells are required to effectively eradicate or contain Mycobacterium tuberculosis-infected cells. A variety of cytokines are involved to ensure productive "cross talk" between macrophages and T lymphocytes. For instance, infection of macrophages with mycobacteria leads to effective interleukin-7 (IL-7) and IL-15 secretion, and both cytokines are able to maintain strong cellular immune responses of alpha/beta and gamma/delta T cells. Here we show that either cytokine is able to enhance survival of M. tuberculosis-infected BALB/c mice significantly compared to application of IL-2, IL-4, or phosphate-buffered saline (as a control). Enhanced survival could be achieved only when IL-7 or IL-15 was delivered as a treatment (i.e., 3 weeks postinfection), not when it was administered at the time of infection. Increased survival of M. tuberculosis-infected animals was observed following passive transfer of spleen cells harvested from M. tuberculosis-infected, IL-7- or IL-15-treated animals, but not after transfer of spleen cells obtained from mice which received either cytokine alone. Histological examination revealed that IL-7 and IL-15 failed to significantly impact on the number and composition of granulomas formed or the bacterial load. Our data indicated that administration of IL-7 or IL-15 to M. tuberculosis-treated animals resulted in a qualitatively different cellular immune response in spleen cells as reflected by increased tumor necrosis factor alpha and decreased gamma interferon secretion in response to M. tuberculosis-infected antigen-presenting cells.
authors.affiliation: Department of Medical Microbiology, Johannes Gutenberg University, Mainz, Germany. maeurer@mail.uni-mainz.de
authors.forename: M J
authors.initials: MJ
authors.lastname: Maeurer
authors.forename: P
authors.initials: P
authors.lastname: Trinder
authors.forename: G
authors.initials: G
authors.lastname: Hommel
authors.forename: W
authors.initials: W
authors.lastname: Walter
authors.forename: K
authors.initials: K
authors.lastname: Freitag
authors.forename: D
authors.initials: D
authors.lastname: Atkins
authors.forename: S
authors.initials: S
authors.lastname: Störkel
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D016207:Cytokines / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D019409:Interleukin-15 / Q000008:administration & dosage / Q000276:immunology*; D015851:Interleukin-7 / Q000008:administration & dosage / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology / Q000401:mortality* / Q000473:pathology
chemical_list: D016207:Cytokines; D019409:Interleukin-15; D015851:Interleukin-7