Maturational changes of lymphocyte surface antigens in human blood: comparison between fetuses, neonates and adults.

The objective of this study was to investigate the maturational changes of lymphocyte surface antigens during ontogeny from fetuses to adults using the proven whole blood lysis technique. Two-color flow cytometric analysis of lymphocyte surface markers was performed on 20 fetal blood samples obtained by cordocentesis, 70 cord blood and 30 adult blood samples. The leukocyte count and all T-cell subsets were highest in neonates compared to fetuses and declined into adulthood. In contrast, the percentage of CD2+ T cells (fetal blood 57% versus adult blood 82%; p </= 0.001), CD3+ T cells (fetal blood 52% versus adult blood 77%; p </= 0.001), CD4+ T cells (fetal blood 39% versus adult blood 50%; p </= 0.05) and CD8+ T cells (fetal blood 15% versus adult blood 24%; p </= 0.001) showed a significant increase from fetuses to adults. The absolute and relative amounts of B cells were highest in fetuses (fetal blood 547 x 10(6)/l, 18%) followed by a steady decline to adulthood (adult blood 243 x 10(6)/l, 13%; p </= 0.001). The discordance between the absolute and relative size of lymphocyte subpopulations emphasizes the consideration of both variables in the assessment of lymphocyte maturation. The presented data may contribute to a better knowledge of the maturation of the immune system. Copyright 2000 S. Karger AG, Basel