The fate of donor-type ABO blood group antigen expression in liver grafts in ABO-incompatible adult living donor liver transplantation.

BACKGROUND/PURPOSE: Donor-type ABO blood group antigens (dABOAgs) have been detected in ABO-incompatible adult living donor liver transplantation (ABOi ALDLT) grafts, but their fate and role in ABOi ALDLT rejection remain uncertain.

METHODS

The 0-day, <1-month, and 1-year serial liver graft biopsies from 30 ABOi ALDLT recipients were retrospectively evaluated. ABO antigen expression was quantitatively and serially measured by the mean number of positively stained vascular structures (endothelium of the capillaries, arteries, hepatic veins, and portal veins) within the portal tracts (sS).

RESULTS

The dABOAg sS counts of 0-day, <1-month, and 1-year liver graft biopsies (32.3, 20.8, and 20.6, respectively) decreased significantly (p < .001). Early rejection in the <1-month biopsy was observed in 8/30 (26.7%) recipients, four (13.3%) of whom showed antibody-mediated rejection. The sS counts tended to rebound in grafts showing early rejection, with minimal changes from the 0-day to <1-month period, but increased to pre-transplantation levels after 1 year, compared to that in grafts without early rejection (36.0, 20.4, 19.6 vs. 23.7, 21.9, 23.0, respectively; p = .040).

CONCLUSIONS

While dABOAg expression decreased after ABOi ALDLT, recipients showing early rejection showed sustained graft dABOAg expression. Therefore, dABOAg expression may be involved in the mechanism of accommodation in ABOi transplantation.