title: Toxic epidermal necrolysis: effector cells are drug-specific cytotoxic T cells.
abstract: BACKGROUND
  Toxic epidermal necrolysis (TEN) is a very rare but extremely severe drug reaction characterized by widespread apoptosis of epidermis with extensive blisters. We previously found drug-specific cytotoxic CD8 T lymphocytes in the blisters of a single patient.
  
  
  OBJECTIVE
  To confirm the role of drug specific cytotoxic lymphocytes in a larger series, to test the cytotoxicity on keratinocytes, and to look for cross-reactivity between chemically related drugs.
  
  
  METHODS
  The phenotype of lymphocytes present in the blister fluids of 6 patients with TEN was analyzed by flow cytometry. Cytotoxic functions were tested by chromium release assay on a variety of target cells (autologous or MHC class I-matched EBV-transformed lymphocytes, autologous keratinocytes) after nonspecific (CD3 monoclonal antibody) or specific (suspected and potentially cross-reactive drugs) activation.
  
  
  RESULTS
  Blister lymphocytes were CD8 + HLA-DR + CLA + CD56 + . In all 6 cases, they were cytotoxic after nonspecific activation. A drug-specific cytotoxicity was observed in 4 cases (3 related to cotrimoxazole and 1 to carbamazepine) toward lymphocytes. Blister cells also killed IFN-gamma-activated autologous keratinocytes in the presence of drug in the 2 patients tested. Blister cells showed a strong immunoreactivity for granzyme B, and cytotoxicity was abolished by EGTA, but not by anti-Fas/CD95, suggesting perforin/granzyme-mediated killing. By using several sulfonamides for testing the specificity of the drug T-cell receptor interaction, we observed cross-reactivity only between 4 structurally closely related medications.
  
  
  CONCLUSIONS
  These results strongly suggest that drug-specific, MHC class I-restricted, perforin/granzyme-mediated cytotoxicity probably has a primary role in TEN.
authors.affiliation: INSERM U448, Hôpital Henri Mondor, Universite Paris XII, F-94010 Créteil, France.
authors.forename: Amal
authors.initials: A
authors.lastname: Nassif
authors.forename: Armand
authors.initials: A
authors.lastname: Bensussan
authors.forename: Laurence
authors.initials: L
authors.lastname: Boumsell
authors.forename: Aurelien
authors.initials: A
authors.lastname: Deniaud
authors.forename: Homayoun
authors.initials: H
authors.lastname: Moslehi
authors.forename: Pierre
authors.initials: P
authors.lastname: Wolkenstein
authors.forename: Martine
authors.initials: M
authors.lastname: Bagot
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Roujeau
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D001768:Blister / Q000276:immunology; D002460:Cell Line; D003429:Cross Reactions; D053804:Granzymes; D006801:Humans; D016130:Immunophenotyping; D015603:Keratinocytes / Q000276:immunology; D008562:Membrane Glycoproteins / Q000502:physiology; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012697:Serine Endopeptidases / Q000502:physiology; D013262:Stevens-Johnson Syndrome / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology
chemical_list: D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases