ANAHEIM, CA—The timing of gamma irradiation influences in vitro characteristics of red cell concentrates (RCCs), according to a new study.
The research showed that RCCs sustain more damage the longer they are stored prior to gamma irradiation and the longer they are stored after irradiation.
However, RCCs from female donors appeared to be less susceptible to irradiation injury, and the additive solution used seemed to affect the level of injury as well.
The study included 7 centers, each of which used its standard RCCs. Five centers used SAGM as additive solution, 1 used AS-3, and 1 used PAGGSM. Two centers used whole blood filtration to prepare leukoreduced RCCs, and 5 centers used buffy coat removal and RCC filtration.
Each center produced 4 pools of 7 RCCs, 2 male and 2 female pools. The units were stored for 43 days, and 1 pool was gamma-irradiated every week.
The researchers also performed weekly sampling to assess in vitro quality parameters. They took an extra sample 24 hours after irradiation and 72 hours after irradiation.
The team found that the age of RCCs at the time of irradiation influenced the rate of increase of hemolysis and the absolute level of hemolysis (P<0.0001).
Hemolysis was higher in units irradiated early and then stored. And the rate of change of hemolysis increased if RCCs were stored for longer before irradiation.
The researchers also found that the age of RCCs at the time of irradiation influenced the rate of increase of potassium and the absolute level of potassium (P<0.0001).
The rate of change of potassium decreased if RCCs were stored longer before irradiation, as potassium was already partly released if the cells were stored longer. Within 7 days of irradiation, potassium levels exceeded those observed in control cells stored for 43 days.
Hemolysis and potassium levels also appeared to be affected by donor sex and the additive solution used.
Hemolysis was lower in RCCs from female donors (P=0.045) and in cells exposed to AS-3 or PAGGSM rather than SAGM (P=0.0597).
Potassium release was lower in cells from female donors (P=0.0032) and in cells exposed to AS-3 rather than PAGGSM or SAGM (P=0.0391).
“This study shows or confirms interesting differences between red cells from males and females, and, of course, we are interested in the underlying mechanism,” Dr de Korte said.
He also said the results of this study will be used to formulate guidance on the maximal pre- and post-irradiation storage time for RCCs with respect to either acceptable hemolysis or potassium release.
Dr de Korte said that, if hemolysis is used as guidance, irradiation should be performed within the first 28 days of storage, and the cells should be used within these 28 days.
If potassium is used as guidance, cells should be used within 7 days of irradiation if the irradiation occurs during the first 10 to 14 days of storage, or the cells should be used immediately after irradiation if irradiation takes place later during storage.