Background: Intestinal transplantation has emerged as a viable therapy for irreversible intestinal failure. Rejection continues to challenge the long-term patient and graft survival. Recently, the incidence of acute rejection has been reduced to 30-40% due to the use of potent immunosuppressive protocols. Herein, we demonstrate the experience of our center in regards to the incidence of acute cellular rejection after intestinal transplantation over almost 25-years.

Methods: Retrospective analysis of 442 intestinal transplants from 1994-2018 with diving the recipients into 5groups depending on the induction immunosuppression used;group1(44/442):high dose steroid(34/44),OKT3(7/44),orcyclophosphamide(3/44);group2:anti-CD25(159/442);group3:alemtuzumab(113/442);group4:rabbit antithymocyte globulin(rATG)(34/442);group5:rATG/rituximab. Types of intestinal transplant included: isolated intestine(I)(n=124), liver-intestine(LI)(n=38), modified multivisceral(MMV)(n=39), and full multivisceral(MV)(n=241) allografts.

Results: The incidence rate of acute rejection of any grade over the first 60 post-transplant months was 59%(262/442). Actuarial estimates of acute rejection free survival at 1,3,6,12,24,60months were 33%,21%,21%,17%,11% and 11% in group1; 53%,42%,37%,35%,29% and 25% in group2; 76%,51%,44%,38%,30% and 23% in group3; 53%,50%,50%,50%,44% and 33% in group4; 85%,69%,68%,61%,58% and 58% in group5, respectively. Factors associated with a decreased risk of acute rejection were recipients in group5(rATG + rituximab) followed by recipients who received MV or MMV allografts then recipients who received alemtuzumab induction(P<0.000001). In group5,rATG/rituximab seemed to be associated with a low risk of developing acute rejection whether during or beyond the first post-transplant month(P<0.000001). Overall incidence of acute severe rejection was 20.6%(91/442). Within each induction immunosuppressive group, the incidence rate of acute severe rejection among recipients who developed acute rejection was 7.6% in group5, 29.4% in group4, 16.8% in group3, 19.5% in group2 and 27% in group1. Overall incidence rates of graft loss during the 1st60 post-transplant months were 13% and 12.2% in recipients who developed acute rejection, respectively. Overall incidence rate of chronic rejection was 1.6%(7/442).

Conclusion: rATG/rituximab induction immunosuppression protocol demonstrated a low hazard rate of developing acute rejection even after the 1st month.