Changes in regulatory T cells in dogs with cancer and associations with tumor type.
BACKGROUND
Regulatory T cells (Treg) have been shown to suppress antitumor immunity and often are increased in humans and rodents with cancer. However, Tregs have not been well studied in dogs with cancer and it is not known if certain tumor types are associated with increased Tregs.


OBJECTIVE
We hypothesized that Treg percentages would be increased in dogs with cancer and that Treg percentages would be higher in dogs with certain types of cancer.


METHODS
The percentages and numbers of Tregs and nonregulatory T cells and B cells were assessed in 34 dogs with cancer and 9 age-matched control dogs. Dogs evaluated included 14 dogs with sarcoma, 7 dogs with carcinoma, 7 dogs with lymphoma, and 6 dogs with mast cell tumor.


METHODS
Numbers and percentages of Tregs, CD4+, and CD8+ T cells and B cells were determined using flow cytometry and compared between control dogs and dogs with cancer.


RESULTS
The percentage of Tregs was significantly increased overall in dogs with cancer compared with control dogs. When tumor types were compared, Treg percentages were significantly increased in dogs with carcinoma. The Treg/CD8 T cell ratio was significantly higher in dogs with cancer compared with control dogs and was also significantly increased in 2 dogs with T-cell lymphoma.


CONCLUSIONS
Treg percentages in blood were increased in dogs with cancer, particularly in dogs with carcinoma. The Treg/CD8 ratio also identified tumor-specific abnormalities in dogs with cancer. These findings indicate that tumor-specific factors may affect Tregs in dogs.
O'Neill
K
K
Department of Clinical Sciences, Animal Cancer Center, Colorado State University, Fort Collins, CO 80523, USA.
Guth
A
A
Biller
B
B
Elmslie
R
R
Dow
S
S
D000818:Animals; D002277:Carcinoma / Q000378:metabolism / Q000662:veterinary; D016022:Case-Control Studies; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs; D008223:Lymphoma / Q000378:metabolism / Q000662:veterinary; D034801:Mastocytoma / Q000378:metabolism / Q000662:veterinary; D009369:Neoplasms / Q000378:metabolism / Q000662:veterinary*; D012509:Sarcoma / Q000378:metabolism / Q000662:veterinary; D050378:T-Lymphocytes, Regulatory / Q000502:physiology*