Early Thrombotic Microangiopathy After ABO-Incompatible Living Donor Kidney Transplantation

Area of Science:

• Nephrology
• Transplantation immunology
• Vascular biology

Background:

• ABO-incompatible (ABOi) kidney transplantation offers an alternative for patients with blood group incompatibility.
• While long-term graft survival is comparable to ABO-compatible (ABOc) transplants, ABOi transplantation carries a higher risk of antibody-mediated rejection (ABMR).
• Early thrombotic microangiopathy (TMA) is a significant complication of ABOi transplantation.

Purpose of the Study:

• To investigate the incidence, clinical presentation, and outcomes of TMA in patients undergoing ABOi kidney transplantation.
• To identify predictive factors for TMA development after ABOi kidney transplantation.
• To evaluate the effectiveness of treatments for TMA in this population.

Main Methods:

• Retrospective multicenter study.
• Inclusion of patients with biopsy-proven or biologically confirmed TMA within one month of ABOi transplantation.
• Comparison with matched controls with favorable initial outcomes and normal biopsies.

Main Results:

• TMA developed in 6.1% of 375 ABOi kidney transplants, with a median onset of 1 day post-transplant.
• Histological evidence of active TMA was found in 80.9% of early graft biopsies.
• Eight early graft losses (30.4%) occurred; higher IgG and IgM anti-blood group antibody (ABGA) levels pre-transplant were predictive of TMA.
• Treatment included plasmapheresis and eculizumab, but prognosis was poor for non-responders.

Conclusions:

• TMA is a significant complication of ABOi kidney transplantation, occurring early and associated with poor prognosis.
• Pre-transplant IgG and IgM ABGA levels are predictive of TMA, but hemagglutination assays are imperfect markers.
• Further research is needed to improve TMA prediction and management in ABOi kidney transplantation.