title: HLA expression and tumor-infiltrating immune cells in uveal melanoma.
abstract: BACKGROUND
  In uveal melanoma, both the amount of tumor-infiltrating cells and the level of expression of HLA antigens are quite variable. We hypothesized that low levels of HLA expression lead to a lack of antigen presentation, which might prevent proper immunologic recognition of the tumor. This lack of recognition might subsequently lead to low levels of tumor-infiltrating cells.
  
  
  METHODS
  To test this hypothesis, we determined the type and number of tumor-infiltrating cells in tumor sections from 24 uveal melanomas. We applied monoclonal antibodies directed against different types of immune cells and compared the results with the expression of HLA class I and class II antigens on the tumor cells.
  
  
  RESULTS
  Infiltrating immune cells were observed in all uveal melanomas (although in small amounts), with a predominance of T lymphocytes. Significant positive correlations were observed between the number of CD3+ cells (T lymphocytes) and monomorphic HLA class I expression, allele-specific HLA-A2 and Bw4 expression, and HLA class II expression. Furthermore, the number of CD4+ cells (T helper cells, monocytes/ macrophages) and of CD11b+ cells (monocytes/macrophages) was significantly correlated with the level of monomorphic HLA class I expression.
  
  
  CONCLUSIONS
  These data support our hypothesis that low levels of HLA expression (and therefore a lack of presentation of tumor-specific antigens) may lead to a low level of tumor infiltrate.
authors: Department of Ophthalmology, University Hospital Leiden, The Netherlands.
authors: I
authors: I
authors: de Waard-Siebinga
authors: C G
authors: CG
authors: Hilders
authors: B E
authors: BE
authors: Hansen
authors: J L
authors: JL
authors: van Delft
authors: M J
authors: MJ
authors: Jager
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000276:immunology; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007962:Leukocytes / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008297:Male; D008545:Melanoma / Q000276:immunology*; D008875:Middle Aged; D014604:Uveal Neoplasms / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II