ABO-Incompatible Transplantation without Conventional Induction Immunosuppression (IL-2RB or Depleting agents)

Background Transplantation across ABO blood group ( ABOI-Tx) has facilitated to increase donor pool for living donor kidney transplantation. Increased risk of rejection despite augmented immunosuppression has been the concern for many transplant programs in initiating a ABOI-TX program. The benefits on long term graft surivial with induction immunosuppression in immunologically low risk individuals is still not clear. ABOI-Tx recipients are subjcted to increased immunosuppression prior to transplant which could provide and an opportunity to transplant without induction with IL2-R blockers or Lymphocyte depleting agents. Aim Aim of our study is to analyze the outcome of our series of 25 consecutive ABOI-Tx patients who underwent transplantation without routine Thymoglobulin or IL2R-blocker induction. Methods Our study is a prospective observational study for first 25 consecutive patients who had undergone ABOI-Tx from two tertiary care centers in Kerala, India having the same IS protocol. Anti-A and anti-B titers ≤ 1:512 by Gel-method(Biorad) were accepted for desensitization. All patients underwent CDC-crossmatch, Flow-crossmatch and Luminex-anti-HLA-antibody-screen. Desensitization regimen included- Rituximab 200mg on Day -21, Triple IS- Prednisolone 10mg, MMF 1000mg and Tacrolimus 0.05mg/bodywt from Day -14 and Plasma-exchange(PLEX) 3-4 sessions from day -7 to attain titer of 1:8 prior to transplantation. Transplantation was done without induction IS. Results Twenty five patients underwent ABOI-Tx from both centers. Twenty recipients were male. Average age was 34±8 yrs with follow-up of 431±298 days. Eight donors were spouse, 13 were parents and 3 siblings. Average age of donor was 46.3± 10.5years. Twenty-two patients have normal functioning transplant with creatinine 1.23± 0.2 mg/dL. Kaplan-Meier analysis showed patient survival of 91.2% and death censored graft survival of 95.6% at 32 months (Figure 1). Two patients were lost; one on post-op day(POD)3 due to ACS and second on POD-22 due to fungal sepsis. One graft loss occurred due to post-transplant HUS with no evidence of rejection. Of the functioning 22 allograft-recipients one had cellular rejection which resolved with pulse steroids; one developed HUS due to CNI which recovered with PLEX and switch to non-CNI based IS. One patient developed AMR on POD-4 which was completely reversed with PLEX and augmentation of IS. Three patients had CMV viremia and one 3 had BKV viremia ; all resolved with treatment and tailoring of IS. Conclusion Achieving acceptable anti A/B titers prior to transplantation is the most critical step in ABOI-Tx. Avoidance of induction IS can decrease the cost and infectious complications. Our data shows the there is no increased incidence of rejections in the first post transpalnt year for immunologically low risk individuals from histocompatibility standpoint undergoing ABOI-Tx without induction immunosuppression. Figure 1 Sreesan A Sreedharan. Ranjith Narayanan.