title: Alterations of lymphocyte subpopulations in healthy dogs with aging and in dogs with cancer.
abstract: Changes in an individual's immune status are considered major contributing factors towards the morbidity of cancer and mortality of aging. To evaluate age-related changes in the immune status of dogs, the immunophenotypes (CD3, CD4, CD8 and CD21) of peripheral blood lymphocytes were measured in 160 healthy dogs aged from 1 to 17 years, and in 365 dogs with various tumors and at various stages. In healthy dogs, the absolute numbers of white blood cells, lymphocytes, and CD3(+), CD4(+) and CD21(+) lymphocytes decreased significantly with age. The relative percentages of lymphocytes and CD4(+) cells decreased significantly, while CD8(+) cells increased significantly with age. The CD4:CD8 ratio showed a significant age-related decrease. In contrast, dogs with tumors possessed significantly lower absolute numbers and relative percentages of all lymphocyte phenotypes, while the CD4:CD8 ratio was significantly higher than in age-matched controls. The relative percentages of CD3(+) and CD8(+) lymphocytes were significantly lower in dogs with distant metastases compared with dogs without metastases, and the CD4:CD8 ratio increased with advanced stage. These observations illustrate the significant changes in immune status with age and the presence of marked immunological defects in a large-scale study of dogs with advanced tumors.
authors.affiliation: Laboratory of Veterinary Clinical Oncology, Small Animal Clinical Sciences, Graduate School of Veterinary Medicine, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu, Hokkaido 069-8501, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Watabe
authors.forename: Shinya
authors.initials: S
authors.lastname: Fukumoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Komatsu
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Endo
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kadosawa
mesh_terms: D000375:Aging / Q000097:blood / Q000276:immunology*; D000818:Animals; D001772:Blood Cell Count / Q000662:veterinary; D016516:CD4-CD8 Ratio / Q000662:veterinary; D004285:Dogs / Q000097:blood / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D016130:Immunophenotyping / Q000662:veterinary*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D009369:Neoplasms / Q000097:blood / Q000276:immunology*; D018709:Statistics, Nonparametric; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*