X‐irradiation and gamma‐irradiation inactivate lymphocytes in blood components

BACKGROUND: Irradiation of selected blood components is standard practice for the prevention of transfusion-associated graft-versus-host disease (TA-GvHD). Currently, gamma-irradiation is the most widely used form of irradiation, but there is an increasing interest in X-irradiation, which is considered to be functionally equivalent and safer. However, there is a paucity of contemporary data regarding the ability of X-irradiation to inactivate lymphocytes in blood components. Therefore, the effect of gamma- and X-irradiation on lymphocyte viability and function in blood components was compared. STUDY DESIGN AND METHODS: Lymphocytes were isolated from venous blood by density gradient centrifugation, spiked into plasma/SSP+ to simulate a blood component, and either gamma- or X-irradiated. The phenotype of the isolated lymphocytes was confirmed. Lymphocyte viability was measured using a LIVE/DEAD assay, and function was assessed using mixed lymphocyte culture and CD69 expression post-phorbol-12 myristate 13-acetate (PMA) stimulation. RESULTS: Lymphocyte viability and CD69 expression following PMA stimulation were significantly reduced by both gamma-irradiation and X-irradiation in simulated blood components. Allorecognition and allostimulation were also significantly reduced by both gamma-irradiation and X-irradiation. CONCLUSION: Lymphocyte viability and function are reduced to a similar extent by gamma- and X-irradiation in simulated blood components. As such, X-irradiation is suitable for the irradiation of blood components and, in terms of lymphocyte inactivation, could be used instead of gamma-irradiation.