title: Decreased ratio of CD8+ T cells to regulatory T cells associated with decreased survival in dogs with osteosarcoma.
abstract: BACKGROUND
  Increased numbers of regulatory T cells (Treg) and decreased ratios of CD8+ T cells to Treg have been shown to correlate with decreased survival times (ST) in humans with certain malignancies. A possible connection between Treg and ST in dogs with cancer has not been investigated previously.
  
  
  OBJECTIVE
  The purpose of this study was to compare numbers of Treg and T lymphocyte subsets in dogs with osteosarcoma (OSA) to those of healthy dogs and to determine whether pretreatment values were associated with disease-free interval or with ST. We hypothesized that Treg numbers would be increased in dogs with cancer and that dogs with a high percentage of Treg would have a poorer prognosis.
  
  
  METHODS
  Twelve client-owned dogs with appendicular OSA were entered into a prospective clinical trial. Twenty-two healthy dogs were used as controls.
  
  
  METHODS
  The percentages and numbers of Treg and CD4+ and CD8+ T cells in blood, lymph nodes, and tumors were determined with flow cytometry and compared between dogs with OSA and control dogs.
  
  
  RESULTS
  Dogs with OSA had significantly fewer circulating CD8+ T cells and significantly more Treg compared with healthy dogs. The CD8/Treg ratio also was significantly lower in dogs with OSA compared with control dogs. In dogs with OSA, a decreased CD8/Treg ratio was associated with significantly shorter STs.
  
  
  CONCLUSIONS
  These data support a role for Treg in the immune control of canine OSA and suggest that determination of the CD8/Treg ratio may be useful for assessing outcomes.
authors.affiliation: Department of Clinical Sciences, Animal Cancer Center, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Biller
authors.forename: A
authors.initials: A
authors.lastname: Guth
authors.forename: J H
authors.initials: JH
authors.lastname: Burton
authors.forename: S W
authors.initials: SW
authors.lastname: Dow
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology*; D004285:Dogs; D012516:Osteosarcoma / Q000401:mortality / Q000662:veterinary*; D011237:Predictive Value of Tests; D050378:T-Lymphocytes, Regulatory / Q000502:physiology*
chemical_list: D000970:Antineoplastic Agents