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

Abstract 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.