Supernatant reduction of stored gamma-irradiated red blood cells minimizes potentially harmful substances present in transfusion aliquots for neonates.

BACKGROUND: In neonate transfusion, the use of a dedicated red blood cell (RBC) unit decreases donor exposure. A separate safety measure involves gamma irradiation of the RBCs to abrogate the possibility of transfusion-associated graft-versus-host disease. However, in combination, storage of gamma-irradiated RBCs leads to accumulation of potentially harmful substances in the supernatant.

STUDY DESIGN AND METHODS: For this study, RBCs were pooled and split into three study arms. Centrifugation or gravity was used to pack RBCs of matched units thereby reducing the amount of supernatant that would be present in neonate transfusion aliquots; these were compared to matched control units. Supernatant measurements of potassium, hemoglobin (Hb), RBC microvesicle (RMV) content, and mannitol were made in aliquots prepared weekly up to 21 days after gamma irradiation. RBC morphology and osmotic fragility were also assessed to determine if supernatant reduction methods affected the storage lesion.

RESULTS: Potassium and mannitol were significantly decreased in transfusion aliquots prepared with either of the supernatant reduction methods. On Day 21, potassium levels from supernatant-reduced aliquots were below those of Day 7 control aliquots. A decrease in free Hb was only detected on Day 21 in centrifuged aliquots. RMVs were significantly reduced in centrifuged aliquots and significantly increased in gravity-settled aliquots. The only measurable effect on storage lesion was a small increase in osmotic fragility of the RBCs subjected to supernatant reduction.

CONCLUSION: Supernatant reduction by centrifugation effectively reduces potassium, mannitol, and RMVs in aliquots from gamma-irradiated RBCs stored up to 21 days.