Prolonged wait times among highly sensitized HLA-B46 homozygous kidney transplant candidates

Individuals who are homozygous for HLA-B46 lack shared epitopes with most other HLA-B antigens and are capable of developing antibodies against all non-self B antigens including Bw4 and Bw6 epitopes. We identified a series of B46 homozygous kidney transplant candidates with long wait times and high cPRAs.

A retrospective observational analysis was conducted on HLA typing and antibody profiles of deceased donor kidney waitlist candidates at the University of California, Davis. Waiting times among calculated panel reactive antibody (cPRA) and sex subgroups were compared using one-way ANOVA.

Among 1,772 waitlist candidates, we found seven that were B46-homozygous (all Asian, four females, three males), with three of the seven having cPRAs > 99.98%. The median wait time for the four females was 4,654 days. The highly-sensitized B46 female subgroup had significantly longer waiting times than males (median 1,071 days) and for all other > 99.50% cPRA patients (median 2,299 days).

These highly-sensitized B46 homozygous candidates had a very small pool of HLA-compatible donors and experienced extremely long waiting times. Future studies are needed using registry data to confirm these findings and assess outcomes.