title: Selective IL-10 inhibition of HLA-DR expression in IFN-gamma-stimulated human retinal pigment epithelial cells.
abstract: OBJECTIVE
  Human RPE cells express HLA-DR antigens, bind leukocytes via ICAM-1, and secrete IL-8 and MCP-1, which attract and activate leukocytes. Since little is known concerning endogenous cytokines that may alter ocular immunologic and inflammatory mechanisms, we investigated whether IL-10, an immunosuppressive cytokine, modulates these HRPE features.
  
  
  METHODS
  IL-10 effects on HLA-DR and ICAM-1 were examined by HRPE exposures to: (1) IFN-gamma (10-1000 U/ml) + IL-10 (1-100 U/ml) and (2) IL-10 pre-incubation followed by IFN-gamma + IL-10. Immunohistochemistry for HLA-DR and ICAM-1 was graded by masked observers. Flow cytometric analysis quantitated HRPE HLA-DR and ICAM-1. Effects of IL-10 on IL-1 beta (0.2 or 2 ng/ml)-, or TNF-alpha (0.2 or 2 ng/ml)-induced IL-8 and MCP-1 secretion and gene expression were assessed using enzyme-linked immunosorbent assay (ELISA) and Northern blot analysis.
  
  
  RESULTS
  HLA-DR expression, detected by immunohistochemistry and flow cytometric analysis, showed dose-dependent increases to IFN-gamma. IL-10 pre-/co-incubation, but not co-incubation alone, markedly reduced HLA-DR expression, but did not modulate constitutive or IFN-gamma-induced ICAM-1. IL-10 alone did not induce MCP-1 or IL-8 secretion or steady-state mRNA expression, nor modulate IL-1 beta-, TNF-alpha- or IFN-gamma-induced IL-8 or MCP-1.
  
  
  CONCLUSIONS
  This study suggests that HRPE HLA-DR antigens are selectively inhibited by IL-10, but the timing of IL-10 exposure may be crucial.
authors.affiliation: Department of Ophthalmology, University of Michigan, Ann Arbor 48105, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Boorstein
authors.forename: S G
authors.initials: SG
authors.lastname: Elner
authors.forename: Z M
authors.initials: ZM
authors.lastname: Bian
authors.forename: R M
authors.initials: RM
authors.lastname: Strieter
authors.forename: S L
authors.initials: SL
authors.lastname: Kunkel
authors.forename: V M
authors.initials: VM
authors.lastname: Elner
mesh_terms: D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D046508:Culture Techniques; D006684:HLA-DR Antigens / Q000378:metabolism*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D016753:Interleukin-10 / Q000494:pharmacology*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*
chemical_list: D018932:Chemokine CCL2; D006684:HLA-DR Antigens; D016209:Interleukin-8; D018799:Intercellular Adhesion Molecule-1; D016753:Interleukin-10; D007371:Interferon-gamma