Effects of Age and Nutrition on Expression of CD25, CD44, and l-Selectin (CD62L) on T-cells from Neonatal Calves*

Effects of the plane of nutrition and age on the proliferation and activation of lymphocyte subsets from milk replacer-fed calves were investigated in vitro. Holstein calves were fed a standard (0.45 kg/d of a 20% crude protein, 20% fat milk replacer, n = 4) or intensified (1.14 kg/d of a 28% crude protein, 20% fat milk replacer, n = 4) diet from 1 to 8 wk of age. Average daily weight gain of intensified-diet (0.66 kg/d) calves was greater than that of standard-diet (0.27 kg/d) calves. Relative to the pokeweed mitogen-induced responses of CD4+ cells from steers (5 to 6 mo of age), CD4+ cells from 1-wk-old calves showed decreased proliferative activity, delayed increase in CD25 expression, and no demonstrable increase in CD44 expression or decrease in CD62L expression. Calf CD8+ and γδT-cell receptor+ cells, unlike T-cells from the older animals, did not demonstrate decreased expression of CD62L after stimulation with mitogen. The increased expression of CD44 by mitogen-stimulated γδT-cell receptor+ cells from older animals was not seen in γδT-cell receptor+ cells from 1-wk-old calves. At wk 8 of age, mitogen-induced proliferation and expression of activation antigens by T-cells from standard-fed calves were similar to responses of T-cells from steers indicating rapid maturation of T-cell function during the neonatal period. Feeding calves an intensified milk replacer was associated with decreased proliferation of mitogen-stimulated CD4+, CD8+, and γδT-cell receptor+ cells; decreased CD25 expression by mitogen-stimulated CD4+ and CD8+ cells; and decreased CD44 expression by mitogen-stimulated CD8+ cells. These results indicate that the functional capacity of the calf's T-cell population becomes more adult-like during the first weeks of life and suggest that nutrition modulates T-cell function during this period of immune maturation.