Maternal immune memory and sex differences in living donor kidney transplant outcomes.

Women have higher rates of rejection and allograft failure not due to death than men. Offspring living kidney donor transplants provide an opportunity to assess the role of maternal immune memory in outcome differences between sexes. Among adult living kidney donor recipients in the Scientific Registry of Transplant Recipients from 2000 to 2018, the cumulative incidence of graft loss was higher in female than that in male recipients (P < .001). Among women, the adjusted hazard ratio (AHR) for graft loss was similar in offspring and nonoffspring donor transplant recipients (AHR, 1.07; 95% CI, 0.94-1.22; P = .3), whereas male recipients of offspring donor kidneys had a lower risk of graft loss than those of nonoffspring donor recipients (AHR, 0.87; 95% CI, 0.77-0.99; P = .03). Among women, offspring donor recipients had a higher adjusted odds ratio (AOR) for rejection (AOR, 1.33; 95% CI 1.06-1.67; P = .02), but among men, the odds of rejection were similar in offspring and nonoffspring donor recipients (AOR, 1.15; 95% CI, 0.95-1.39; P = .14). The findings indicate a role for maternal immune memory in sex differences in kidney transplant outcomes that should be verified with further immunologic studies.