Fetal Properties in Red Blood Cells of Newborn Infants

Abstract

SummaryIn order to identify the fetal features in neonatal erythrocytes, cord blood was separated into seven fractions of varying specific density. Cell age in the single fractions was ascertained by means of reticulocyte count, glutamic-oxalacetic transaminase activity, and hemoglobin F concentration. The same procedures were used with blood of adults. With the exception of the fraction of neonatal blood with the highest specific density, the blood from neonates and adults correlated well for cell age and specific density. The highest specific density fraction of neonatal blood was found to contain a higher proportion of younger cells.The comparison of enzyme activities in the single fractions between neonates and adults showed that a high activity of glucose-6-phosphatedehydrogenase and enolase and a low activity of phosphofructokinase are typical fetal signs of neonatal cells. SpeculationThe changing constitution of red blood cells (RBC), which were observed during the first months of life may be a part of the differentiation process. Due to their good accessibility and their relatively simple metabolism, erythrocytes from neonates can serve as a good in vivo model that helps to clarify the process of differentiation.As a part of the differentiation process the properties distinguishing neonatal from adult erythrocytes (17) are lost during the first months of life and are replaced by the corresponding adult properties. To examine the factors and mechanisms that govern the process of differentiation, it is first necessary to define the fetal properties of neonatal red cells.Due to the shorter lifespan of fetal erythrocytes and the higher proportion of young cells in blood of newborn infants, direct comparison with adult red cells is not possible. Therefore, in this study, a fractionation method was used that separated blood in subpopulations of cell age to better define the typical fetal signs of neonatal red cells. MATERIALS

Oxidative Stress in Newborn Erythrocytes

“…The heavy layer was enriched with HbF (80% compared with 58% in the light layer). This value indicates the presence of older cells in the heavy layer, as is also demonstrated in the report of Gahr et al (18). Oxidized Hb and GSH levels did not differ in the heavy and light layers.…”

Characteristics and Functional Properties of Red Cells during the First Days of Life

“…Indeed after 4 days the density o f RBC markedly increases as shown by the presently reported data on RBC separation into fractions of different density. In this regard, our results agree per fectly with those of previous papers in as far as the distribution of density-separated RBC and the enzyme activities in the different fractions of cord blood [19][20][21] are con cerned. However, the analysis of the varia tion of erythrocyte densities by the assay of enzyme activities in the different fractions clearly indicates that during the short period of 4 days the RBC populations shift towards denser fractions.…”

Characteristics of hexokinase, pyruvate kinase, and glucose‐6‐phosphate dehydrogenase during adult and neonatal reticulocyte maturation

“…In order to provide experimental evidence for a biphasic decay pattern, it is a prerequisite to obtain red blood cell fractions comprising up to 100% reticulocytes, a proportion largely exceeding the 10-20 % reticulocytes usually obtained in the least dense fractions of regular density centrifugations [3,6]. We have composed the density gradient to such an extent that after centrifugation only 0 5 2 % of the applied cells comprised the lowest density fraction.…”