title: Corrective effects of interleukin-12 on age-related deficiencies in IFN-gamma production and IL-12Rbeta2 expression in virus-specific CD8+ T cells.
abstract: Interleukin-12 receptor beta2 (IL-12Rbeta2) has been shown to be selectively expressed on Th1 T cell subsets, and we have previously shown that influenza-specific CD8+ cytotoxic T lymphocyte (CTL) deficiency in old mice was associated with deficient Th1 (interferon-gamma [IFN-gamma]) cytokine production. This study tested whether IL-12Rbeta2 expression was also deficient in CD8+ CTL from old mice and the effect of IL-12 treatment on these responses. Splenic lymphocytes from influenza-primed old and young BALB/c mice were stimulated with influenza virus in vitro with and without IL-12 and then enriched for CD8+ T cells. IFN-gamma was significantly reduced, whereas IL-4 and IL-12p40 (an antagonist of IL-12 function) were evaluated in old when compared with young mice. This was true for secreted protein measured by ELISA and for mRNA levels quantitated by RT-PCR. IL-12Rbeta2 mRNA expression in CD8+ CTL was also significantly reduced in old mice. IL-12 treatment in vitro caused significant upregulation of IFN-gamma and IL-12Rbeta2 and downregulation of IL-4 in CD8+ T cells from old mice and young mice. The present demonstration of an age-related downregulation in IL-12Rbeta2 expression and our previous data showing reduced IFN-gamma and elevated IL-4 production provide strong evidence that CD8+ CTL deficiency in aging results from a Th1/Th2 cytokine production switch. Agents that increase IL-12Rbeta2 expression and redirect Th2 to Thl immune responses are likely to enhance CD8+ CTL-mediated control of viral infections in aging.
authors.affiliation: Department of Microbiology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: C L
authors.initials: CL
authors.lastname: Acuna
authors.forename: K C
authors.initials: KC
authors.lastname: Switzer
authors.forename: L
authors.initials: L
authors.lastname: Song
authors.forename: R
authors.initials: R
authors.lastname: Sayers
authors.forename: I N
authors.initials: IN
authors.lastname: Mbawuike
mesh_terms: D000375:Aging / Q000235:genetics / Q000276:immunology*; D000818:Animals; D001483:Base Sequence; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D009980:Influenza A virus / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D018664:Interleukin-12 / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics*; D053707:Receptors, Interleukin-12; D018417:Th1 Cells / Q000187:drug effects / Q000276:immunology; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology
chemical_list: D016207:Cytokines; D017931:DNA Primers; C508443:Il12rb2 protein, mouse; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053707:Receptors, Interleukin-12; D018664:Interleukin-12; D007371:Interferon-gamma