THE EFFECT OF AGE ON THE DISTRIBUTION OF LYMPHOCYTE AND NEUTROPHIL GRANULOCYTE SUBSETS IN THE PERIPHERAL-BLOOD OF DOG

Samples of peripheral blood obtained from Beagle dogs of different age were examined for total and differential leukocyte counts and distrib ution of lymphocyte subpopulations. Subsets of leukocytes were counted using the cell counter and light microscope of blood films. Monoclona l antibodies against canine homologue of CD3, CD5, CD4, CD8, and CD21 were used for the detection of lymphocyte subsets by flow cytometry. F irst day after the parturition the neutrophil to leukocyte ratio was 2 .22. Over the first week a decrease of this ratio occurred till the va lues about 0.63. Since the second week of age an increase of neutrophi l count was recorded connected with extended neutrophil to leukocyte r atio till the value 1.87 at one month of age. The ratio had been exten ding till the value 1.97 at the age 3-5 years. The ratio between T and B lymphocytes was 1.2 and 1.3 first day after parturition and at the age of one month, respectively. The ratio had been extending till the value 6.3 at the age of 1-2 years. The extension was caused essentiall y by a decrease of the absolute B lymphocyte count. On day 1 after par turition almost all T-lymphocytes were CD4 positive and their count ev en increased over the first week. Since the second week of age no chan ges in CD4 positive lymphocyte count have been recorded. CD8 positive lymphocyte count increased over the age of the examined dogs. Thus the ratio of CD4 and CD8 positive lymphocytes was reduced from 13.7 on da y 1 after parturition to 2.0 in age category 3-5 years.