title: T cell populations propagating in the peripheral blood of patients with drug eruptions.
abstract: BACKGROUND
  In the non-immediate type of drug eruptions, the populations of circulating T cells may be altered as a consequence of T cell responses to a culprit drug.
  
  
  OBJECTIVE
  The aim of this study was to investigate differences among the types of drug eruptions in propagating T cell populations of the patients' peripheral blood.
  
  
  METHODS
  The type of eruptions were divided into three categories: (1) generalized maculopapular eruption (MPE), (2) erythema multiforme (EM)/Stevens-Johnson syndrome (SJS), and (3) drug-induced hypersensitivity syndrome (DIHS) or drug rash with eosinophilia and systemic symptoms (DRESS). T cell populations were phenotypically analyzed by flow cytometry in the percentage of T helper (Th) 1 (CXCR3+CD4+), Th2 (CCR4+CD4+), Tc1 (CXCR3+CD8+), and Tc2 (CCR4+CD8+) subsets and their activation states as assessed by CD69, CD25 or HLA-DR positivity.
  
  
  RESULTS
  Upon occurrence of both MPE and EM/SJS, Th2 cells outnumbered Th1 cells, whereas Tc1 and Tc2 cells differentially predominated in EM/SJS and MPE, respectively. An increase of HLA-DR+CD8+ cells in EM/SJS type provided another supportive evidence for Tc1 stimulation. In DIHS, during the development of the second wave of eruption and/or liver dysfunction associated with anti-HHV6 antibody elevation, CD4+ cells were gradually decreased, but CD8+ cells were inversely increased. Tc1 cells were increased as well as Th1 cells. Finally, in all the three groups, there existed a considerable number of CD25+CTLA-4-CD4+ T cells.
  
  
  CONCLUSIONS
  Our study suggests that Th2/Tc2 and Th2/Tc1 cells mediate MPE and EM/SJS, respectively, and Tc1 cells are involved in the pathogenesis of DIHS at the late stage.
authors.affiliation: Department of Dermatology, University of Occupational and Environmental Health, 1-1 Iseigaoka, Kitakyushu 807-8555, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nishio
authors.forename: Kunio
authors.initials: K
authors.lastname: Izu
authors.forename: Kenji
authors.initials: K
authors.lastname: Kabashima
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Tokura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004342:Drug Hypersensitivity / Q000276:immunology / Q000473:pathology*; D004892:Erythema Multiforme / Q000276:immunology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010267:Parapsoriasis / Q000276:immunology / Q000473:pathology*; D013262:Stevens-Johnson Syndrome / Q000276:immunology / Q000473:pathology*; D016176:T-Lymphocyte Subsets / Q000473:pathology*; D013602:T-Lymphocytes, Cytotoxic / Q000473:pathology; D018417:Th1 Cells / Q000473:pathology; D018418:Th2 Cells / Q000473:pathology