title: IL-7 in the cell-mediated immune response to a human pathogen.
abstract: The goal of the present study was to investigate the role of IL-7 in regulating immune responses to infection. Leprosy provides a model for understanding human immune responses to infection; the disease presents as a spectrum in which the clinical manifestations correlate with the levels of cell-mediated immunity to the pathogen, Mycobacterium leprae. To determine whether IL-7 is produced at the site of infection in leprosy, we used the PCR to measure IL-7 and IL-7R mRNA in skin lesions. IL-7 mRNA was more strongly expressed in the tuberculoid form of the disease, in which the infection is limited (mean cpm = 48 +/- 8; n = 11), as compared with the progressive lepromatous form (17 +/- 2; n = 11). IL-7R mRNA, both membrane-bound and soluble forms, were also more strongly expressed in tuberculoid lesions, although these differences were not as striking as those for IL-7. The cellular source of IL-7 included Ag-stimulated monocytes and IFN-gamma-induced keratinocytes. M. leprae-induced PBMC responses in tuberculoid patients involved up-regulation of IL-7 and IL-7R mRNA and was IL-7 dependent. In contrast, M. leprae did not induce IL-7 mRNA in lepromatous patients, and their T cell responses were weakly augmented by rIL-7. These data suggest that IL-7, produced at the site of disease, contributes to the cell-mediated immune response to human pathogens.
authors.affiliation: Division of Dermatology, University of California, Los Angeles, School of Medicine, CA 90095.
authors.forename: P A
authors.initials: PA
authors.lastname: Sieling
authors.forename: L
authors.initials: L
authors.lastname: Sakimura
authors.forename: K
authors.initials: K
authors.lastname: Uyemura
authors.forename: M
authors.initials: M
authors.lastname: Yamamura
authors.forename: J
authors.initials: J
authors.lastname: Oliveros
authors.forename: B J
authors.initials: BJ
authors.lastname: Nickoloff
authors.forename: T H
authors.initials: TH
authors.lastname: Rea
authors.forename: R L
authors.initials: RL
authors.lastname: Modlin
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D006801:Humans; D015851:Interleukin-7 / Q000096:biosynthesis* / Q000276:immunology*; D015603:Keratinocytes / Q000276:immunology; D007918:Leprosy / Q000276:immunology*; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009166:Mycobacterium leprae / Q000276:immunology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D018123:Receptors, Interleukin / Q000096:biosynthesis; D020395:Receptors, Interleukin-7; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015851:Interleukin-7; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D020395:Receptors, Interleukin-7