title: Heightened expression of MICA enhances the cytotoxicity of NK cells or CD8+T cells to human corneal epithelium in vitro.
abstract: BACKGROUND
  Major-histocompatibility-complex class I-related chain A (MICA) antigens are the ligands of NKG2D, which is an activating or coactivating receptor expressed on human NK cells and CD8+T cells. We sought to determine whether MICA expression in human corneal epithelium (HCE) could affect the cytotoxicity mediated by NK cells or CD8+T cells.
  
  
  METHODS
  Cell cultures of HCE were harvested from human donor eyes. Flow cytometric analysis and ELISA was performed to determine the levels of MICA expression on HCE. Then, HCE was transfected with a lentivirus vector expressing MICA and GFP. Flow cytometric analysis, RT-PCR, western blot and ELISA were performed to check the levels of MICA expression. For cytotoxicity testing, allogeneic NK cells and CD8+T cells were isolated from peripheral blood mononuclear cells of healthy volunteers by magnetic cell sorting. The cytolytic activity of NK cells and CD8+T cells was assessed against MICA-transfected HCE (NK cells: E:T ratio = 3:1; CD8+T cells: E:T ratio = 10:1) using the nonradioactive cytotoxicity detection kit lactate deshydrogenase.
  
  
  RESULTS
  Surface expression of MICA on corneal epithelium was identified at a low level. A cell line of stable human MICA-transfected corneal epithelium was successfully established. Heightened expression of MICA on HCE was found to promote the cytotoxicity mediated by NK cells or CD8+T cells, which could be blocked by an anti-MICA antibody.
  
  
  CONCLUSIONS
  MICA molecules may contribute to cytotoxic responses mediated by activated immune effector cells in corneal epithelium immunity.
authors.affiliation: Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, School of Shanghai Medicine, Fudan University, 83 Fenyang Road, Shanghai, 200031, China.
authors.forename: Jiaxu
authors.initials: J
authors.lastname: Hong
authors.forename: Ting
authors.initials: T
authors.lastname: Qiu
authors.forename: Tingting
authors.initials: T
authors.lastname: Qian
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Yu
authors.forename: Junyi
authors.initials: J
authors.lastname: Chen
authors.forename: Qihua
authors.initials: Q
authors.lastname: Le
authors.forename: Xinghuai
authors.initials: X
authors.lastname: Sun
authors.forename: Jianjiang
authors.initials: J
authors.lastname: Xu
mesh_terms: D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D014162:Transfection / Q000379:methods
chemical_list: D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A