Evidence for a suppression of apoptosis in early postnatal life

Background. In fetal life the rates of proliferation and apoptosis are high . We studied if the rate of apoptosis decreases after birth, by measuring t he soluble (s) forms of Fas-Fas ligand and Tumor necrosis factor receptor 1 (TNFR1)-TNF-alpha which attenuate apoptosis. Subjects and methods. Blood was drawn from the umbilical cord and from a pe ripheral vein on day 1 and 4 of life in 35 infants and sFas, sFas ligand, s TNFR1 and sTNF-alpha were determined by enzyme immunoassays. Data were anal yzed by paired t-test and Pearson's correlation analysis. Results. sFas and sTNF increased significantly from birth to day 4 of life (P=0.033 and p <0.0001 respectively), while sTNFR1 increased significantly from birth to day 1 of life (p <0.0001) followed by a significant decrease on day 4 of life (P <0.0001). The levels of sFas and sTNF-alpha on day 1 co rrelated with those on day 4 (r=0.677, p <0.0002 and r=0.525, p <0.007 resp ectively). sFAS ligand was not detectable in any specimen. Conclusion. The increasing concentrations of the soluble molecules, sFas, s TNF-alpha and sTNFR1 might indicate that apoptosis may be downregulated in early postnatal life.