title: Anti-Gal-mediated targeting of human B lymphoma cells to antigen-presenting cells: a potential method for immunotherapy using autologous tumor cells.
abstract: OBJECTIVE
  The residual tumor cells remaining after completion of standard chemotherapy and radiation treatment in B lymphoma patients, may be eradicated by active immunotherapy that stimulates tumor-specific T lymphocytes. Irradiated autologous lymphoma cells expressing tumor-associated antigens (TAA) may serve as a potential tumor vaccine, provided that they are effectively targeted to the antigen-presenting cells (APC). We propose exploiting the natural anti-Gal antibody in order to target vaccinating tumor cells to APC. Anti-Gal constitutes 1% of IgG in human serum and interacts specifically with the alpha-gal epitope (Galalpha1-3Galphalbeta1-4GlcNAc-R).
  
  
  METHODS
  Alpha-gal epitopes were synthesized in vitro on the membrane of primary lymphoma cells by using the recombinant glycosylation enzyme alpha1,3galactosyltransferase (alpha1,3GT). Processed tumor cells were opsonized by purified anti-Gal antibodies and studied for uptake (phagocytosis) by APC including monocyte-derived macrophages and dendritic cells. Cross-presentation of tumor antigens after phagocytosis of processed MHC-I negative lymphoma cells was measured by activation of a tumor-specific CD8+ T-cell line.
  
  
  RESULTS
  We demonstrate synthesis of alpha-gal epitopes on freshly isolated B lymphoma cells of various types following the use of the recombinant enzyme alpha1,3GT. The subsequent binding of anti-Gal to the de novo synthesized alphagal epitopes opsonizes these tumor cells for effective uptake by macrophages and dendritic cells, through phagocytosis mediated by FcgammaR1 (CD64). Moreover, anti-Gal-mediated phagocytosis resulted in cross-presentation of TAA by dendritic cells.
  
  
  CONCLUSIONS
  This study suggests that immunization with irradiated autologous lymphoma cells processed to express alpha-gal epitopes will result in anti-Gal-mediated, in vivo targeting of the autologous tumor vaccine to APC.
authors.affiliation: Research and Development Laboratory, EFS Rhône-Alpes, Grenoble, EA 2021, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Manches
authors.forename: Joel
authors.initials: J
authors.lastname: Plumas
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Lui
authors.forename: Laurence
authors.initials: L
authors.lastname: Chaperot
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Molens
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Sotto
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Bensa
authors.forename: Uri
authors.initials: U
authors.lastname: Galili
mesh_terms: D000606:Amino Sugars / Q000276:immunology; D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000276:immunology; D002144:Callithrix; D019496:Cancer Vaccines / Q000627:therapeutic use*; D002478:Cells, Cultured / Q000276:immunology; D005700:Galactosyltransferases / Q000235:genetics / Q000494:pharmacology; D006031:Glycosylation; D006801:Humans; D007113:Immunity, Innate; D007114:Immunization; D007074:Immunoglobulin G / Q000276:immunology*; D007167:Immunotherapy / Q000379:methods*; D008213:Lymphocyte Activation; D016393:Lymphoma, B-Cell / Q000276:immunology / Q000473:pathology* / Q000628:therapy; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000276:immunology* / Q000528:radiation effects; D009439:Neuraminidase / Q000494:pharmacology; D010587:Phagocytosis; D017452:Receptors, IgG / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014312:Trisaccharides / Q000276:immunology*
chemical_list: D000606:Amino Sugars; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D007074:Immunoglobulin G; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D014312:Trisaccharides; C076569:alpha-galactosyl epitope; C000458:N-acetyllactosamine; D005700:Galactosyltransferases; C047006:N-acetyllactosaminide alpha-1,3-galactosyltransferase; D009439:Neuraminidase