title: β2-Microglobulin-free HLA-G activates natural killer cells by increasing cytotoxicity and proinflammatory cytokine production.
abstract: Human leukocyte antigen-G (HLA-G) is a nonclassical HLA class-I molecule and plays a role in tissue specific immunoregulation. Many studies have addressed functional aspects of β2-microglobulin (β2m)-associated HLA-G1. β2m-free HLA-G has been found in human placental cytotrophoblasts and pancreatic β cells although its function remains unclear. In the present study, we investigated the function of β2m-free HLA-G by transfecting HLA-G1 and -G3 into human β2m deficient rat pancreatic β cell carcinoma (BRIN-BD11) cells. RT-PCR and western blots studies confirmed high expression of HLA-G1 and -G3 in -G1 and -G3 transfectants, respectively. HLA-G1 and -G3 were detected mainly in intracellular compartments of BRIN-BD11 transductants by confocal fluorescent microscopy and flow cytometry. Functional analysis revealed that β2m-free HLA-G promoted xenogeneic cytotoxic lysis of BRIN-BD11 cells by natural killer (NK) cells and increased production of IL-1β, TNF-α, and IFN-γ. Stimulation of cytotoxic lysis was impaired by blocking the MAPK and DNA-PKcs pathways in NK cells. Importantly, treatment with 33mAb, a KLR2DL4 receptor agonist, induced NK-mediated cytotoxic lysis of BRIN-BD11 cells transfected with a mock vector. Our data suggest that β2m-free HLA-G activates NK cells via engagement of KLR2DL4 receptors.
authors.affiliation: Escape Therapeutics, Inc., San Jose, CA 95138, USA.
authors.forename: Longmei
authors.initials: L
authors.lastname: Zhao
authors.forename: Bhamini
authors.initials: B
authors.lastname: Purandare
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Basil M
authors.initials: BM
authors.lastname: Hantash
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D059951:HLA-G Antigens / Q000235:genetics / Q000276:immunology*; D006801:Humans; D016899:Interferon-beta / Q000096:biosynthesis / Q000276:immunology; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000276:immunology; D007694:Killer Cells, Natural / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects; D051381:Rats; D054345:Receptors, KIR2DL4 / Q000819:agonists / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000276:immunology; D001613:beta 2-Microglobulin / Q000172:deficiency* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D059951:HLA-G Antigens; D053583:Interleukin-1beta; D054345:Receptors, KIR2DL4; D014409:Tumor Necrosis Factor-alpha; D001613:beta 2-Microglobulin; D016899:Interferon-beta