Imunidade celular em caninos neonatos - do nascimento ao 45° dia de idade (Cellular immunity in canine newborns - from birth to the 45 th day of life)

The aim of this study was to evaluate the immune development of newborn canines, evaluating the cellular immunity by analysis of leukocyte and lymphocyte totals and sub-population of T lymphocytes (CD4+ and CD8+) by the flow cytometry technique. Thirty neonatal mongrel dogs of both sexes were used, at 3, 10, 17, 24, 31, 38 and 45 days of age. The total leukocyte count to 45 days (11639±3574/µL) was significantly greater than on the third day of age (8740±1812) (p<0.05); There were no differences between the total count of lymphocytes at 45 days in relation to the third day of age. As for the subpopulations of CD4+ and CD8+, CD4+ cell percentages, at three days of age (24.9±16.8) they were inferior when compared to the average between the 10 th , 24 th and 31 st day (35.5), and CD8+ cells, on the third day, were lower compared with averages from the 10 th and 31 st day of age. It can be concluded that the subpopulations of CD4+ and CD8+ cells undergo oscillations during development, with growing postnatal levels obtained at three days old. The CD4:CD8 ratio showed superiority to the first cell type, and the largest relationship between CD4 + and CD8 + occurred on the third day of age. Based on the results obtained in this study, the differences noted in lymphocyte populations weekly showed the dynamics of these cells during the neonatal period. 