The effect of gamma irradiation on the quality of apheresis platelets during storage for 7 days

BACKGROUND: This study compares the quality of gamma-irradiated versus nonirradiated platelet (PLT) concentrates (PCs) during storage for 7 days as assessed by various in vitro methods. A new technique, free oscillation rheometry (FOR), which measures clotting time and coagulum elasticity, was also used to evaluate the PLT function. STUDY DESIGN AND METHODS: Single-donor PLTs were collected by apheresis technique (n = 20). The PLTs from each donor were divided into two PCs, one gamma-irradiated with 25 Gy and the other used as a nonirradiated control. Blood gases, metabolic variables, and swirling were analyzed from Day 0. Samples taken on Days 1, 5, and 7 were also analyzed for hypotonic shock response (HSR), P-selectin, and glycoprotein (GP)Ib expression by flow cytometry and coagulation by FOR. RESULTS: Swirling, HSR, and the percentage of GPIb-expressing cells were well maintained for 7 days of storage. pH was always within accepted range (6.4-7.4). Glucose decreased and lactate increased during the storage period (p < 0.05). P-selectin expression increased during storage (p < 0.05). The FOR clotting time remained constant, whereas the build-up of elasticity was slower after storage (p < 0.05). No difference was found between irradiated and nonirradiated PCs. CONCLUSION: The results indicate a well-preserved quality of gamma-irradiated apheresis PLTs during storage for 7 days as assessed by in vitro methods, with no difference compared to nonirradiated PLTs.