Purpose: We have demonstrated that the long-term outcome of ABO incompatible living donor kidney transplantation (ABOiKT) was comparable to those of ABO compatible KT(ABOcKT). Since 2010, new protocol using low dose rituximab (RIT) without plasmapheresis(PP) was administered to recipients with low titer anti-donor blood group antibody titer (ABGAb) was less than x64. The purpose of this study was to evaluate the efficacy of this new protocol for ABOiKTx.
Method: 279 recipients underwent kidney transplantation between September 2010 and August 2017. 43 patients who received PP before kidney transplantation because of positivity of donor specific antibody, high titer ABGAb or a recurrence prevention of original disease were excluded. Consequently, 236 recipients were enrolled in this study. The patients were divided into two groups: ABOiKT (n=41) and ABOcKT (n=195). No recipient received splenectomy before kidney transplantation. As a standard protocol, all patients received quadruple immunosuppressive therapy including calcineurin inhibitor, methylprednisolone and mycophenolate mofetil. In addition, as a desentization protocol for ABOiKT, RIT was administered twice on day -10 and -1 day before transplantation at a dose of 100 mg/body. To evaluate the efficacy and safety of this new protocol for ABOiKT, graft survival, clinical acute rejection rate, late-onset neutropenia (LON) and infectious complication were compared between the two groups.
Results: Median baseline titers of ABGAb in ABOiKT was x16 (0-x64). Overall 1-,3- and 5-year graft survival rates were 98.3%, 96.8% and 96.8% in ABOcKT and 97.1%, 97.1% and 97.1% in ABOiKT, respectively (p=0.950). There was no significant difference in the clinical T cell mediated acute rejection rates (17 (8.7%) in ABOcKT vs. 3 (7.3%) in ABOiKT (p=0.770)) nor antibody mediated acute rejection rates (3 (1.5%) in ABOcKT vs. o (0%) in ABOiKT (p=0.424)). Ocurrence rates of LON were significantly higher in ABOiKT (18 (43.9%)) than in ABOcKT (11 (5.6%)) (p<0.0001). However, the rates of infectious complication that needed inpatient hospital care or modification of immunosuppression were no significantly different between two groups (p=0.256).
Conclusion: Our current desensitization protocol using low dose RIT without splenectomy was safe and effective for ABOiKTx. Though infectious complication did not increase, we had to pay attention to LON after ABOiKT. Moreover, pretransplant antibody removal would not be prerequisite for ABOiKTx with low titer ABGAb.