title: HLA-G protein expression as a potential immune escape mechanism in classical Hodgkin's lymphoma.
abstract: Classical Hodgkin's lymphoma (cHL) is characterized by the presence of an abundant reactive infiltrate, lacking effective cytotoxic responses. Especially in Epstein-Barr virus (EBV)-negative cHL, the neoplastic Hodgkin-Reed-Sternberg (HRS) cells have lost protein expression of major histocompatibility complex (MHC) class I, enabling escape from cytotoxic T lymphocyte (CTL) responses. However, downregulation of MHC class I generally induces natural killer (NK) cell activation. The paucity of NK cells in the reactive infiltrate of cHL and the systemic NK cell deficiency observed in cHL patients led us to investigate the expression of human leukocyte antigen (HLA)-G, which is known to inhibit NK-cell- and CTL-mediated cytotoxicity. By immunohistochemistry, HLA-G protein was expressed by HRS cells in 54% (95/175) of cHL cases. This expression was associated with absence of MHC class I on the cell surface of HRS cells (P < 0.001) and EBV-negative status (P < 0.001). Previously, genetic markers located in the proximity of the HLA-A and HLA-G genes had been shown to be associated with susceptibility to EBV-positive cHL. In the present study, these markers associated with MHC class I protein expression but not with presence of HLA-G. Our results suggest that induction of HLA-G protein expression in HRS cells contributes to the modulation of immune responses observed in cHL.
authors.affiliation: Department of Pathology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. a.diepstra@path.umcg.nl
authors.forename: A
authors.initials: A
authors.lastname: Diepstra
authors.forename: S
authors.initials: S
authors.lastname: Poppema
authors.forename: M
authors.initials: M
authors.lastname: Boot
authors.forename: L
authors.initials: L
authors.lastname: Visser
authors.forename: I M
authors.initials: IM
authors.lastname: Nolte
authors.forename: M
authors.initials: M
authors.lastname: Niens
authors.forename: G J
authors.initials: GJ
authors.lastname: Te Meerman
authors.forename: A
authors.initials: A
authors.lastname: van den Berg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D002648:Child; D005260:Female; D005819:Genetic Markers; D005838:Genotype; D006680:HLA Antigens / Q000235:genetics / Q000378:metabolism*; D015234:HLA-A Antigens / Q000235:genetics; D059951:HLA-G Antigens; D004854:Herpesvirus 4, Human / Q000302:isolation & purification; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D006689:Hodgkin Disease / Q000235:genetics / Q000276:immunology* / Q000821:virology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D016539:Reed-Sternberg Cells / Q000276:immunology / Q000821:virology
chemical_list: D005819:Genetic Markers; D006680:HLA Antigens; D015234:HLA-A Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I