Complement activation and long-term graft function in ABO-incompatible kidney transplantation

Area of Science:

• Nephrology
• Immunology
• Transplantation Science

Background:

• ABO-incompatible kidney transplantation is generally successful in the short term, attributed to graft accommodation.
• The mechanism of accommodation, potentially involving complement inhibition, remains unclear.
• Incomplete complement inhibition might explain inferior long-term graft function in ABO-incompatible transplants compared to ABO-compatible ones.

Purpose of the Study:

• To investigate the link between pre-transplant anti-ABO antibodies, complement activation, and long-term kidney transplant outcomes.
• To elucidate the role of complement activation in ABO-incompatible kidney transplantation.

Main Methods:

• A cohort study comparing 27 ABO-incompatible kidney transplantations with 108 ABO-compatible controls (2008-2013).
• Analysis of graft and patient survival, kidney function (creatinine clearance, MDRD), and rejection rates.
• Correlation of pre-transplant anti-ABO IgG titers with complement activation markers (C5b-9) and T-cell mediated rejection.

Main Results:

• No significant differences in overall graft or patient survival were observed.
• ABO-incompatible recipients exhibited lower kidney function at three months post-transplant (P=0.02) due to higher rates of early T-cell mediated rejection (33% vs 15%, P=0.03).
• Elevated pre-transplant anti-ABO IgG titers correlated with C5b-9 staining and T-cell mediated rejection, suggesting a role for complement activation in rejection.

Conclusions:

• Complement activation by anti-ABO antibodies, potentially through C5a-mediated T-cell co-stimulation, may contribute to impaired long-term graft function in ABO-incompatible kidney transplantation.
• Understanding this mechanism could lead to improved strategies for ABO-incompatible kidney transplantation.