Donor white blood cell survival and cytokine profiles following red blood cell transfusion in Australian major trauma patients

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.

Does Transfusion of Red Blood Cells Impact Germline Genetic Test Results?

Purpose: molecular testing is often indicated for recently transfused patients. However, there are no guidelines regarding the potential interference from donor DNA or whether it is necessary to wait for a period of time post-transfusion prior to genetic testing. While the majority of patients are transfused in the non-trauma setting using leukoreduced (LR) red blood cell products, the degree of leukoreduction varies among centers and is not universally practiced. Methods: whole blood units collected from anonymous donors were used in an in vitro transfusion model. One unit was split: half being leukoreduced simulating a leukopenic recipient and half left untreated. Donors were simulated by leukoreduced, partially leukoreduced (PLR), or non-leukoreduced units, transfused in 2, 5, or 16 unit equivalents. DNA from the combinations were subjected to short tandem repeat (STR) analysis for chimerism detection. Results: donor DNA was not detectable in any of the LR combinations, but detected in the PLR combinations, ranging from 0.1 to 1.5% donor DNA in the immunocompetent recipient and 6.3–27.8% in the leukopenic recipient. Non-LR donor DNA was also detected (13–95%). Conclusion: donor-derived DNA from leukoreduced blood products is unlikely to interfere with the interpretation of germline genetic testing in immunocompetent recipients but may interfere in immunocompromised recipients.