title: CD4dullCD8bright double-positive T-lymphocytes have a phenotype of granzyme Bpos CD8pos memory T-lymphocytes.
abstract: BACKGROUND
  T-lymphocytes that co-express CD4 and CD8 antigens may be found in small percentages in the peripheral blood of healthy individuals, and have a CD4brightCD8dull phenotype. CD4dullCD8bright T-lymphocytes have been found only in temporal association with some viral infections.
  
  
  METHODS
  Four-colour flow cytometric analysis of peripheral blood mononuclear cells from a renal transplant recipient with cytomegalovirus infection was performed.
  
  
  RESULTS
  A small but clearly distinguishable subpopulation of CD4dullCD8bright double-positive T-lymphocytes was detected, that exhibited phenotypic characteristics of cytotoxic T-lymphocytes and were granzyme B positive. Furthermore, no naive cells appeared to be present within this subpopulation.
  
  
  CONCLUSIONS
  CD4dullCD8bright double-positive T-lymphocytes are enriched for memory and effector cytotoxic T cells.
authors.affiliation: Department of Internal Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands.
authors.forename: R J
authors.initials: RJ
authors.lastname: Rentenaar
authors.forename: P C
authors.initials: PC
authors.lastname: Wever
authors.forename: F N
authors.initials: FN
authors.lastname: van Diepen
authors.forename: P T
authors.initials: PT
authors.lastname: Schellekens
authors.forename: P M
authors.initials: PM
authors.lastname: Wertheim
authors.forename: I J
authors.initials: IJ
authors.lastname: ten Berge
mesh_terms: D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D005260:Female; D053804:Granzymes; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D008875:Middle Aged; D012697:Serine Endopeptidases / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases