Decreased ratio of CD8+ T cells to regulatory T cells associated with decreased survival in dogs with osteosarcoma.
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.
Biller
B J
BJ
Department of Clinical Sciences, Animal Cancer Center, Colorado State University, Fort Collins, Colorado, USA.
Guth
A
A
Burton
J H
JH
Dow
S W
SW
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*
D000970:Antineoplastic Agents