title: Direct recognition of LPS by human but not murine CD8+ T cells via TLR4 complex.
abstract: LPS comprises a major PAMP and is a key target of the immune system during bacterial infection. While LPS can be recognised by innate immune cells via the TLR4 complex, it is unknown whether T lymphocytes, especially CD8(+) T cells are also capable of doing so. We report here that naive human CD8(+) T cells, after activation by TCR stimulation, express surface TLR4 and CD14. These activated CD8(+) T cells can then secrete high concentrations of IFN-gamma, granzyme and perforin in response to LPS. These effects can be specifically inhibited using siRNA for TLR4. Furthermore, LPS can synergize with IL-12 to polarize the CD8(+) T cells into cytotoxic T-cell 1 (Tc1) that produce IFN-gamma but not IL-4, with or without TCR activation. Moreover, CD8(+)CD45RO(+) memory T cells constitutively expressed TLR4 and markedly enhanced IFN-gamma production when stimulated with LPS. In contrast, activated murine CD8(+) T cells lack TLR4 and CD14 expression and fail to respond to LPS for proliferation and cytokine production. Thus, human but not murine CD8(+) T cells are able to directly recognise bacterial LPS via LPS receptor complex and TLR4 provides a novel signal for the activation of effector and memory human CD8(+) T cells.
authors.affiliation: Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, UK.
authors.forename: Mousa
authors.initials: M
authors.lastname: Komai-Koma
authors.forename: Derek S
authors.initials: DS
authors.lastname: Gilchrist
authors.forename: Damo
authors.initials: D
authors.lastname: Xu
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D053804:Granzymes / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D018664:Interleukin-12 / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects; D051218:Lymphocyte Antigen 96 / Q000235:genetics; D051379:Mice; D008809:Mice, Inbred C3H; D008817:Mice, Mutant Strains; D054353:Perforin / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D016176:T-Lymphocyte Subsets / Q000187:drug effects / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000906:Antibodies; D017252:CD3 Complex; C495377:LY96 protein, human; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D051218:Lymphocyte Antigen 96; D034741:RNA, Small Interfering; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D054353:Perforin; D018664:Interleukin-12; D007371:Interferon-gamma; D017493:Leukocyte Common Antigens; D053804:Granzymes