title: 4-1BB regulates NKG2D costimulation in human cord blood CD8+ T cells.
abstract: Ligation of NKG2D, a potent costimulatory receptor, can be either beneficial or detrimental to CD8(+) cytotoxic T cell (CTL) responses. Factors for these diverse NKG2D effects remain elusive. In this study, we demonstrate that 4-1BB, another costimulatory receptor, is an essential regulator of NKG2D in CD8(+) T cells. Costimulation of NKG2D caused down-modulation of NKG2D, but induced 4-1BB expression on the cell surface, even in the presence of TGF-beta1, which inhibits 4-1BB expression. Resulting NKG2D(-)4-1BB(+) cells were activated but still in an immature state with low cytotoxic activity. However, subsequent 4-1BB costimulation induced cytotoxic activity and restored down-modulated NKG2D. The cytotoxic activity and NKG2D expression induced by 4-1BB on NKG2D(+)4-1BB(+) cells were refractory to TGF-beta1 down-modulation. Such 4-1BB effects were enhanced by IL-12. In contrast, in the presence of IL-4, 4-1BB effects were abolished because IL-4 down-modulated NKG2D and 4-1BB expression in cooperation with TGF-beta1, generating another CD8(+) T-cell type lacking both NKG2D and 4-1BB. These NKG2D(-)4-1BB(-) cells were inert and unable to gain cytotoxic activity. Our results suggest that 4-1BB plays a critical role in protecting NKG2D from TGF-beta1-mediated down-modulation. Co-expression of NKG2D and 4-1BB may represent an important biomarker for defining competency of tumor infiltrating CD8(+) T cells.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine; 2 Walther Oncology Center, Indianapolis, IN 46202-5181, USA. yjkim@iupui.edu
authors.forename: Young-June
authors.initials: YJ
authors.lastname: Kim
authors.forename: Myung-Kwan
authors.initials: MK
authors.lastname: Han
authors.forename: Hal E
authors.initials: HE
authors.lastname: Broxmeyer
mesh_terms: D053330:4-1BB Ligand / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000276:immunology; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D005312:Fetal Blood / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology; D015847:Interleukin-4 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000276:immunology; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic / Q000276:immunology*; D055607:Receptors, Natural Killer Cell; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
chemical_list: D053330:4-1BB Ligand; C527085:KLRK1 protein, human; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; D053773:Transforming Growth Factor beta1; D015847:Interleukin-4