November 11, 2017

Assessing Age-Related Changes in Peripheral Blood Leukocyte Phenotypes in Labrador Retriever Dogs Using Flow Cytometry

The research studies restructuring of the immune system of Labrador Retrievers based on their age. The research has significance as changing immunology influences life expectancy, mortality, and morbidity in all species of dogs.

 Previous studies suggest that increased age leads to the general reduction in protective immunity—shown by reduced cell number, proliferative capacity, and cellular dysfunction—which is interrelated with increased infection and degenerative diseases such as cancer and arthritis. Increased intake of micronutrient reduces infection, and this suggests possibility of immune function alleviation through sufficient nutrition.

 Previous studies also suggest that peripheral leukocyte decreases as age increases especially in beagles and Labrador Retrievers. To investigate WBC population variety, blood samples which contains lymphocytes, monocytes and granulocytes are analyzed. Fluorescence activated cell sorting techniques are used to study leukocyte population change in relation to age. This method becomes the basis of this research that focuses on the immunological life stage of Labrador Retriever.

 Vaccinated, healthy male and female Labrador Retrievers of the age between 6 months to 170 months are tested. Of 122 dogs, 71 were females and 51 were males. Their blood samples were analyzed with lysed whole blood staining and triple-color flow cytometric analysis. T cells, B cells, and lymphocytes population and subgroups within them were investigated. Lymphocytes, monocytes, and granulocytes values were calculated as percentages.

 The results indicated that the T cells which is also called T-lymphocytes increased significantly as the dog aged. B cells decreased, which means aged dogs have less adapted antibody response. There were no significant changes in CD14, monocytes, and granulocytes population.

 One of the prominent change that could be seen was the big increase of T cells, and this suggests that as the dog ages, his or her memory cells increase, and that their normal proliferative response to various potential antigens also increase.

 TH1 and TH2 are the subgroups within CD4 lymphocyte group. Though T cells increased TH1 decreased. This suggests that age reduces the potential for monocyte populations that control infections. TH2 also decreased, and this suggests possible reduce of the B cells activities that produce antibodies. CD4 and CD8 are variety of T cells. CD4:CD8 ratio also decreased as age increased, and this suggests that as the dog ages, risks also increases. So ultimately risks increase but their abilities to fight against them also increase.

The paper suggests increased sample size as one of the possible improvements, and points out the fact that different breeds have different life stage and therefore different immune cycle as one of its limitation. Though it made clear that immunological status does change according to the age.


​Reviewed by Yunji Baik

​Full article: