Impact of catch-up vaccinations on anti-HLA antibody response in pediatric kidney transplant candidates

Background: Efforts have been concentrated on improving vaccination administration during the pretransplant evaluation period. However, concern for human leukocyte antigen (HLA) sensitization subsequent to vaccination exists. Methods: A retrospective review of pediatric kidney transplant candidates (PKTCs) ≤18 years old who had received vaccinations between February 1, 2017 and November 30, 2019 was conducted. Emergence of de novo anti-HLA antibody (HLA-Ab) 3–4 weeks postvaccinations detected by the Luminex single antigen bead assay (SAB) was evaluated. Outcomes assessed included change in the HLA-Ab mean fluorescence intensity (MFI) ≥25% from baseline, and change in preexisting HLA-Ab MFI strength, categorized as weak: 1000–2999; moderate: 3000–9999; and strong: ≥10 000. Results: Sixty vaccinations were administered to 14 patients. Forty-one potential de novo HLA-Ab were detected in five patients. After additional antibody panel testing, 5/41 potential de novo HLA-Ab were determined to be HLA specific; the remaining 36 were deemed nonspecific. The 5 de novo HLA-Ab were observed in three patients and were deemed weak antibody (Ab). Median MFI showed a significant increase for nonspecific Ab, but not de novo HLA-Ab. Median MFI values were deemed transient at 7–10 week follow-up. No HLA-donor–specific Ab developed posttransplant in the patients who developed de novo HLA-Ab. Conclusion: Vaccination resulted in a transient increase in non-HLA–specific Ab. The majority of responses were non-HLA specific, hypothesized to be related to denatured antigens on single antigen beads. These data suggest limited clinical impact of vaccinations on the emergence of de novo HLA-Ab.