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

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.

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.

A total of 17 of 93 patients (18.3%) developed anti-HLA antibodies. In the non-irradiated group, allosensitization occurred in 8/39 patients (20.5%) compared to 9/54 (16.7%) in the irradiated group (χ² = 0.22, p = 0.7866). 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).

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.