Allosensitization From Blood Transfusion in Pediatric Solid Organ Transplant Candidates: Impact of Irradiation

BACKGROUND: Up to 30% of patients develop anti-HLA antibodies following a single transfusion with leukoreduced packed red blood cells (pRBCs). While some speculate that irradiation of pRBCs could reduce the risk of allosensitization, its effect in clinical practice remains unclear. METHODS: A single-center, retrospective study was conducted with 93 pediatric solid organ transplant (SOT) candidates from January 2013 to July 2022. All participants had a baseline calculated panel reactive antibody (cPRA) of 0% and underwent repeat cPRA testing at least 28 days after pRBC transfusion to evaluate for de novo allosensitization. Patients were stratified by pRBC preparation: exclusively irradiated pRBC versus any exposure non-irradiated pRBC. The primary outcome was the incidence of interval allosensitization in each group. In multivariable analysis, the number of pRBC transfusions was the only risk factor to increase the odds of allosensitization (OR 1.18, p = 0.004). Number of non-pRBC sensitizing events was paradoxically found to be protective (OR 0.8, p = 0.03). Chronic immunosuppression did not mitigate allosensitization risk, although IVIG was associated with a non-significant risk reduction (OR 0.12, p = 0.07). CONCLUSION: The number of pRBC transfusions remains the strongest modifiable risk factor for pre-transplant allosensitization in pediatric SOT candidates. Irradiation of pRBC did not significantly reduce the risk of transfusion-associated allosensitization in this population. IVIG may have a protective effect and should be further evaluated in a future, better powered study.