Changes in the distribution of αβ and γδ T cells in blood and in lymph nodes from fetal and postnatal lambs

Abstract

We have examined the distribution of αβ and γδ T cells, together with B cells, in a range of lymph nodes and blood before and after birth. The proportions of blood-borne αβ and γδ T cells changed markedly during development with a wave of increasing numbers of blood-borne γδ T cells occurring in the fetus during the last month of gestation and early postnatal life. γδ T cells constituted 18% of T cells in the blood of fetal lambs one month before birth and 60% of T cells in the blood of lambs one month after birth. There were also changes in the numbers of αβ T cells circulating through lymph nodes after birth. The proportion of CD4 + and CD8 + cells in mesenteric nodes increased substantially after birth, whereas that of γδ T cells decreased. Although B cells were present in much larger numbers in ileal lymph nodes in both the fetus and lamb, there was a large increase in the concentration of B cells in all lymph nodes in lambs after birth. In addition to the differences in the distribution of lymphocyte subsets circulating in fetal and postnatal lambs, markedly different growth patterns were also observed between lymph nodes before and after birth.