Present Status of ABO Incompatible Kidney Transplantation in Japan-Lessons From More Than 2,400 Cases to Date-.

Abstract

Introduction: Since the first successful in January 1989, we have performed more than 2,400 ABO incompatible kidney transplantation(ABOIKT) to date.and it accounts for 30% of annual living kidney transplants in Japan. Purpose of this study: From the latest registry, we have reviewed the long term patient and graft survival, and analysed the factors which affected the outcome. Patients and Methods: 2,434 cases were enrolled in this study. Observation period was median 3 years 5 months( 1 day to 23 years 7 months) Average recipient age was 43.7 years. Blood type O accounts for 52%, type A for 25% and type B for 23%. HLA-AB and DR mismatches were 2.13±1.07 and 1.08± 0.65. Results: Overall patient survival rate at 1,5,10,15 and 20 years are 97, 93, 90, 83 and 73%, and graft survival rate are 94, 86, 71, 59, and 52%, respectively. Since 2001, the success rate has dramatically improved that patient survival rate at 1,5,10 years are 97, 95 and 93%, and graft survival rate are 93, 90 and 81%, respectively. 1,147 among 1,672 (68.6%)cases avoided splenectomy after 2001. Before 2000 era, graft survival rate of anti-A/B IgG antibody titer 64 folds and greater group were significantly worse than those with less than 32 folds, however, the difference disappered after 2001 era. Discussion: In the recent decade, we have elucidated the phenomenon of accommodation, and established the strategy of its induction by desensitization in ABOIKT. We have utilized the combination of CNI,MMF, steroids, anti-CD25 mAbs and rituximab which enabled to achieve the accommodation without splenectomy. In our study, the patient and graft outcome had dramatically improved even in patients wirh high preoperative anti A/B antibody titer groups after 2001 era, which was indicated as high risk group for AMR and poor graft outcome before 2000 era. We have really overcome the immunological barrier of ABO-histo-blood broup carbohydrate antigen and antibody in the field of kidney transplantation. Conclusion: ABO-IKTx has become accepted as a therapeutic alternative for end-stage kidney disease. The complete elucidation of the accommodation induction mechanism in near future will open the next door to the upcoming brand-new paradigm of the field of organ transplantation.