Estimation of Adult and Neonatal RBC Lifespans in Anemic Neonates using RBCs Labeled at Several Discrete Biotin Densities

BACKGROUND: Prior conclusions that autologous neonatal red blood cells (RBC) have substantially shorter lifespans than allogeneic adult RBCs were not based on direct comparison of autologous neonatal vs. allogeneic adult RBCs performed concurrently in the same infant. Biotin labeling of autologous neonatal RBCs and allogeneic adult donor RBCs permits concurrent direct comparison of autologous vs. allogeneic RBC lifespan. METHODS: RBCs from 15 allogeneic adult donors and from 15 very low birth weight (VLBW) neonates were labeled at separate biotin densities and transfused simultaneously into the 15 neonates. Two mathematical models that account for the RBC differences were employed to estimate lifespans for the two RBC populations. RESULTS: Mean±SD lifespan for adult allogeneic RBC was 70.1±19.1 d, which is substantially shorter than the 120 d lifespan of both autologous and adult allogeneic RBC in healthy adults. Mean±SD lifespan for neonatal RBC was 54.2±11.3 d, which is only about 30% shorter than that of the adult allogeneic RBCs. CONCLUSION: This study provides evidence that extrinsic environmental factors primarily determine RBC survival (e.g., small bore of the capillaries of neonates, rate of oxygenation/deoxygenation cycles) rather than factors intrinsic to RBC.