title: Importance of the CD3 marker for evaluating changes in rhesus macaque CD4/CD8 T-cell ratios.
abstract: BACKGROUND
  Until recently, there were no CD3 antibodies that crossreacted with rhesus macaque T cells. Consequently, studies relying on CD8 counts or CD4/CD8 ratios enumerated this subpopulation on the basis of CD8+ or CD8bright+ staining. We used a rhesus-specific, anti-CD3 antibody to better define the CD8+ T-cell population, and to show the effects of better measurements on CD4/CD8 ratios and changes in T cells as macaques age.
  
  
  METHODS
  We used three-color flow cytometry to measure CD4 and CD8 populations with and without CD3 costaining. Venous blood samples were obtained from 52 colony-bred macaques between 2 months and 9 years of age.
  
  
  RESULTS
  The CD8+ T cells defined by CD3 and CD8 double staining were approximately 60% of all cells that were stained by CD8 alone. Improved detection of this lymphocyte subset showed that CD4/CD8 ratios were close to the range of 1.5-2.0. Declining CD4/CD8 ratios during aging are predominantly due to decreasing CD4+ T-cell counts.
  
  
  CONCLUSIONS
  Better quantitation of the CD8+ T-cell population showed that the CD4/CD8 ratio was not inverted as had been reported, but is actually very similar to the values observed in human beings. Although the two species differ in the pattern of CD8 expression, the general immune system characteristics are very similar.
authors.affiliation: Wisconsin Regional Primate Research Center, Madison, WI 53706, USA.
authors.forename: M
authors.initials: M
authors.lastname: Dykhuizen
authors.forename: J
authors.initials: J
authors.lastname: Ceman
authors.forename: J
authors.initials: J
authors.lastname: Mitchen
authors.forename: M
authors.initials: M
authors.lastname: Zayas
authors.forename: A
authors.initials: A
authors.lastname: MacDougall
authors.forename: J
authors.initials: J
authors.lastname: Helgeland
authors.forename: E
authors.initials: E
authors.lastname: Rakasz
authors.forename: C D
authors.initials: CD
authors.lastname: Pauza
mesh_terms: D000367:Age Factors; D000818:Animals; D017252:CD3 Complex / Q000032:analysis* / Q000276:immunology*; D015704:CD4 Antigens / Q000032:analysis / Q000276:immunology; D016516:CD4-CD8 Ratio / Q000379:methods*; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology; D016827:CD8 Antigens / Q000032:analysis / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology; D003429:Cross Reactions; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D008253:Macaca mulatta; D008297:Male
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens