B and T lymphocyte subsets in fetal and cord blood: age-related modulation of CD1c expression.

Peripheral blood lymphocytes from fetal, term and adult subjects were analyzed with a panel of B- and T-lymphoid differentiation markers. CD1c +ve and CD5 +ve B cell (IgM +ve) percentage in fetal, cord and adult blood decreased significantly. Fetal and cord blood contained less CD2+ and CD3+ T lymphocytes and a higher percentage of CD38 +ve cells than adult blood. The phenotypic changes occurring during perinatal age in humans relate to the changes in the functional activities of the B and T lymphoid subsets from fetal to postnatal age.