Clinical outcomes of ABO-incompatible kidney transplantation in recipients with extremely high baseline isoagglutinin titers: a two-center experience.

BACKGROUND

ABO-incompatible kidney transplantation (ABOi KT) has become increasingly feasible; however, recipients with very high baseline isoagglutinin titers continue to pose substantial clinical challenges.

METHODS

We conducted a retrospective, two-center review of 15 patients who underwent ABOi KT with baseline anti-A/B immunoglobulin G titers ≥1:1024. All patients received rituximab, therapeutic plasma exchange, and a standardized immunosuppressive regimen. Clinical outcomes-including bleeding complications, biopsy-proven acute rejection (BPAR), opportunistic infections, graft function, and patient survival-were assessed.

RESULTS

The median patient age was 53 years (13 men, 2 women). All but one achieved a preoperative titer ≤1:32 after a median of 10 apheresis sessions (range, 7-16). Two patients required graft nephrectomy due to severe postoperative bleeding. Five patients developed BPAR, comprising T cell-mediated and/or antibody-mediated rejection episodes; notably, only one had a titer of 1:1024 at rejection, while the remainder had titers ≤1:16. Regarding opportunistic viral infections, seven patients developed concurrent cytomegalovirus (CMV) and BK viremia, two had CMV alone, and two had isolated BK viremia. Over a median 9.18-year follow-up (range, 0.04-16.45 years), three experienced graft loss-two from chronic rejection at 6 and 15 years, and one due to sepsis-associated acute kidney injury at 15 years. Two patients died during follow-up: one from cardiovascular disease at 1.2 years and the other from pneumonia at 6 years.

CONCLUSIONS

Despite extremely high baseline isoagglutinin titers, ABOi KT can achieve durable graft survival in carefully selected patients; however, it remains a high-risk procedure carrying a substantial burden of bleeding and infectious complications.