Increased non-transferrin bound iron in plasma-depleted SAG-M red blood cell units.

Abstract

BACKGROUND AND OBJECTIVES: Non-transferrin bound iron (NTBI) is associated with increased morbidity in a number of transfusion-dependent disease states such as the severe haemoglobinopathies. We hypothesized that this may be related to excess NTBI present in plasma-depleted red blood cell units that are free of clear haemolysis. MATERIALS AND METHODS: The level of NTBI was determined using the bleomycin assay in samples from 20 stored plasma-depleted red cell units, at approximate 5-day intervals up to day 33 after donation. Forty units of fresh-frozen plasma (FFP) and 40 units of platelet concentrates were used as negative controls, and samples from 12 units of FFP were also serially assessed. RESULTS: Median [interquartile range (IQR)] NTBI was 0 microm (0-0.35) in samples taken from units 3-10 days after donation. Thereafter, the levels of NTBI increased, becoming significant (median 3.05; IQR: 0.05-6.7 microm) 17-22 days after donation. After 30 days, NTBI was detectable in all red cell units. NTBI was undetectable in platelet concentrates and FFP. CONCLUSIONS: Increased levels of NTBI become detectable 17-22 days after donation and increase further with storage time. This excess NTBI may promote bacterial infection in iron-loaded individuals.