Effect of gamma radiation on the in vitro aggregability of WBC‐reduced apheresis platelets

BACKGROUND: The effect of gamma radiation on single-donor apheresis platelet concentrates (SDPs) has been elucidated only incompletely. The only existing report on the function of SDPs stored in the irradiated state found a deterioration in the in vitro aggregability at the end of shelf life in SDPs divided before irradiation with 1500 cGy. STUDY DESIGN AND METHODS: The in vitro properties of platelets were examined in four series of irradiated and control platelets, each obtained from the same 15 donors. Irradiation with 3000 cGy was performed on Days 0, 3, and 5. Cellular content, aggregability by ADP alone or ADP and epinephrine, spontaneous and induced CD62 expression, β-thromboglobulin release, glucose consumption, lactate production, and pH were measured immediately after preparation and on Days 3 and 5 after donation. RESULTS: Comparable in vitro properties were measured in irradiated and control platelets, whether irradiation was performed on Day 3 or Day 5. However, in platelets irradiated on Day 0, we found a significantly better in vitro aggregability by 20 μM ADP immediately after irradiation and by 10 μM ADP and 2 μM epinephrine at the end of shelf life than was found in the other groups (Day 5 results: Day 0 irradiation: 75 ± 32%; Day 3 irradiation: 45 ± 45%; Day 5 irradiation: 47 ± 41%; control: 40 ± 24%; p<0.05). CONCLUSION: Gamma radiation had no adverse effect on platelet quality in extremely WBC-reduced SDPs. On the contrary, a slight, but significantly better in vitro aggregability was found in SDPs irradiated before storage than in platelets irradiated later during storage and in unirradiated platelets. This increased in vitro aggregability persisted until the end of shelf life.