Effect of oxygen and temperature on the potassium efflux of irradiated, stored red blood cells.

Gamma irradiation of blood is performed to prevent transfusion-associated graft-versus-host disease and can result in an accelerated efflux of intracellular potassium (K+). The oxygen content of the blood and the temperature at which the irradiation is carried out are two variables reported to affect this shift; they were investigated in two separate studies. Study A-Four units of AS-5 red blood cells were each split equally into four transfer bags. One set of transfer bags was stored at 4 degrees C for 42 days (Control), the second set (IRR) was irradiated and stored. The third and fourth groups were oxygenated; the third set (+O2) was placed at 4 degrees C. The fourth set (IRR+O2) was irradiated, then stored. Supernatant K+ and hemoglobin increased in the IRR + O2 group over IRR and Control, +O2 did not rise compared to Control. Study B-Six units of CPDA-1 whole blood were each equally separated into four transfer bags. The first set of bags was placed at 4 degrees C, the second set was irradiated and then stored (IRR). The third group of bags was irradiated and given an 8-hour 22 degrees C incubation prior to storage at 4 degrees C (IRR-22). The fourth set was irradiated, placed at 37 degrees C for 2 hours, then stored. Supernatant K+ was lower during the first 7 days of storage for the IRR-22 and IRR-37 groups compared to IRR, but these increased to IRR levels by day 35. Irradiation of blood products results in an accelerated K+ shift that can be exacerbated by the presence of oxygen. The injury can be partially and temporarily corrected by a post-irradiation incubation at 22 degrees C or 37 degrees C.