Introduction: Blood group incompatibility (ABOi) is a significant barrier to living donor (LD) kidney transplantation (ktx). We describe our ABOi kidney tx desensitization protocol which evolved from our experience with highly HLA sensitized patients.

Patients and Methods: Our protocol consists of MPA starting at day -30. On day -14, Rituximab 1gm is given followed by plasma exchange (PE) qod X 5 treatments. After last PE, IVIG (2gm/kg) is given and tx is scheduled within 1 week. Treatment goal was to decrease titers to ≤ 8 before tx. Patient records were reviewed and outcomes such as graft and pt survival, rates of antibody mediated rejection (AMR) and viral infection rates were examined.

Results: 44 patients (8 ABOi/HLA incompatible and 36 ABOi only) underwent ABOi kidney tx. Baseline isohemagglutinin titers ranged from 2-256 to achieve pre-tx titers ≤ 8 (ranged from 1-32). Induction was either Daclizumab or subcutaneous Alemtuzumab (5 pts. vs. 39 pts.). All pts were maintained on Fk/MMF/Pred post tx. 10 patients had AMR (range 7 days to 20 months post-tx with 60% occurring within 30 days) and received post-tx PE. De novo donor specific antibodies (DSA) occurred in 5% of pts. AMR in the Alemtuzumab vs. Daclizumab group was 21% vs. 40% respectively. AMR was 14% vs. 63% in the ABOi group compared to the ABOi/HLA incompatible group. Overall graft survival was 95% (1 graft loss due to noncompliance and second loss was death with functioning graft) and pt survival was 98% (1 death due to accident). Average serum creatinine was 1.3 mg/dl at last measurement with mean f/u at 27.9 months (range from 1 -77 mo). Post-tx viral infections were seen in 20% of pts (7pts with CMV viremia, 2pts with BK viremia without BK nephritis).

Conclusion: ABOi ktx using a protocol involving Rituximab, pre-tx PE and IVIG without protocol post tx PE appears to be safe and effective. Although AMR was seen in this cohort, graft and patient survival rates did not appear to be compromised. It appears that the use of subcutaneous Alemtuzumab for induction is associated with much lower AMR rates compared to IL-2 receptor antagonists. Pts who are both ABO incompatible and HLA incompatible are at higher risk for AMR and require closer monitoring post tx. Overall, ABOi should no longer be considered a contraindication for tx and ABOi tx protocols could contribute significantly to improving access to LD kidney transplantation.

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