β2-Microglobulin-free HLA-G activates natural killer cells by increasing cytotoxicity and proinflammatory cytokine production

Hum Immunol. 2013 Apr;74(4):417-24. doi: 10.1016/j.humimm.2012.11.022. Epub 2012 Dec 7.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacology
  • Cell Line, Tumor
  • Coculture Techniques
  • Cytotoxicity, Immunologic / drug effects
  • Gene Expression / drug effects
  • HLA-G Antigens / genetics
  • HLA-G Antigens / immunology*
  • Humans
  • Interferon-beta / biosynthesis
  • Interferon-beta / immunology
  • Interleukin-1beta / biosynthesis
  • Interleukin-1beta / immunology
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / drug effects
  • Killer Cells, Natural / immunology*
  • Lymphocyte Activation / drug effects
  • Rats
  • Receptors, KIR2DL4 / agonists
  • Receptors, KIR2DL4 / genetics
  • Receptors, KIR2DL4 / immunology*
  • Signal Transduction / drug effects
  • Transfection
  • Tumor Necrosis Factor-alpha / biosynthesis
  • Tumor Necrosis Factor-alpha / immunology
  • beta 2-Microglobulin / deficiency*
  • beta 2-Microglobulin / immunology

Substances

  • Antibodies, Monoclonal
  • HLA-G Antigens
  • Interleukin-1beta
  • Receptors, KIR2DL4
  • Tumor Necrosis Factor-alpha
  • beta 2-Microglobulin
  • Interferon-beta