T-CELL SUBSETS IN BLOOD AND LYMPHOID-TISSUES OBTAINED FROM FETAL CALVES, MATURING CALVES, AND ADULT BOVINE

Assessment of CD2, CD4, CD8 and gamma delta cell distribution among mo nonuclear cells obtained from the blood and lymphoid tissues of fetal calves, 0-150-day-old calves and adult cows was the focus of this inve stigation. The distributions of some of the lymphocyte subsets in peri pheral blood showed variation in fetal and maturing calves as well as being markedly different from those observed in adult cows. We provide evidence that as early as 1 month prepartum, fetal calves have a full complement of at least four of the major T-cell subsets found in the normal bovine, In blood, CD2(+) were significantly higher at 1, 30 and 90 days of age, CD4(+) and CD8 cells demonstrated a peak in the fetus es that dropped below adult levels from 1 to 120 days of age, and gamm a delta(+) cells were highest at birth and decreased to adult levels b y 150 days of age, Except for the gamma delta(+) cells, the subsets we re significantly higher in lymphoid tissues obtained from fetal and ma turing calves than in the mature animals. All four subsets were signif icantly higher in fetal and young calf splenic tissues, No significant differences were observed in the distribution of the four subsets in thymuses assayed in this study, An interesting pattern was seen in a l ongitudinal study of T-cell subsets that showed 7-8 day cyclical chang es in CD2 and CD4 marked cells in adult peripheral blood.