Derivated fetal haemoglobin as a marker for red cell age in the human fetus reflecting stimulated or impaired red blood cell production

Abstract

We have determined whether derivated fetal haemoglobin (dHbF, consisting of glycated and acetylated HbF) can be used as a cell age marker for fetal red blood cells (RBCs). Cord blood was obtained between 19 and 39 weeks of gestation from 28 alloimmunised anaemic fetuses (23 RhD+ and 5 Kell) and from 20 non-anaemic fetuses and newborns (controls). Density gradient centrifugation was applied to 36 samples (20 RhD+, 15 controls and 1 Kell) to obtain fractions of increasing cell age. Blood samples were used for measurements of mean cellular volume (MCV), mean cell haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), pyruvate kinase activity (PK) and derivated fetal haemoglobin (dHbF) by cation-exchange HPLC. Reticulocytes were counted only in the whole blood samples. In all density gradient separated RBC fractions, the values for MCV, MCH and PK activity decreased and those of MCHC and dHbF increased with increasing density (equivalent to increasing cell age). The mean density was lower for RBCs of the anaemic RHD group (1.072+/-0.007 g/ml) than for the non-anaemic controls (1.077+/-0.005 g/ml) (p<0.05) The RBC density of the Kell sensitised fetus did not differ from those of the controls. In the control group, the values of the cell age markers in whole blood changed significantly with the gestational age, showing an increase of mean age of the erythrocyte population. The best linear relationship was found for dHbF (y=6.28+0.17*weeks; r=0.84; p<0.001). In the anaemic RhD+ fetuses, the RBC age markers did not change with gestational age; the dHbF percentages were lower, and the MCV, MCH, PK values and the reticulocyte counts were higher than in the controls (0.05<p<0.001). The dHbF values of the Kell sensitised fetuses were above (p<0.01) and the reticulocyte counts were below normal (p<0.05) for gestational age. For the anaemic fetuses, a significant number of the dHbF values (86%) and of the reticulocyte counts (78%) differed from the values of the controls (p<0.01). The dHbF percentages in RhD+ fetuses showed the best correlation with the Hb deficit, which is a measure for anaemia (r=-0.81, p<0.0001). We conclude that the percentage derivated HbF may indicate whether the RBC production is normal for gestational age. It may in that sense reflect stimulated or impaired erythropoiesis in alloimmunised haemolytic anaemia.

Accurate Measurements of Fetal Hemoglobin for Neonates with Different Gestational Ages

“…The O 2 -carrying capacity of Hb F 1 is not clear, although it is suspected to be nonfunctional, like glycated Hb or carbamylated Hb (1,34). These Hb variants were observed to be nonfunctional and non responsive to 2,3-diphosphoglycerate (2,3-DPG) binding to release O 2 (35).…”

The measurement of accurate fetal hemoglobin and related oxygen saturation by the hemoximeter

“…Acetylated HbF (HbF1) is a variation of HbF, a posttranslational modification of HbF by acetylation of the Nterminus of γ globin chains [12,13]. Its O 2 carrying capacity was reported as dysfunctional, irresponsive to 2,3 diphosphoglycerate (2,3 DPG) binding to facilitate O 2 release at tissue level [13,14]. Therefore, accurate HbF measurement is essential to assess adequate oxygenation and to prevent O 2 related complications in these neonates [7,15].…”