ABO-incompatible liver transplantation using only rituximab for patients with low anti-ABO antibody titer

Immunology demystified: A guide for transplant hepatologists

Liver transplantation has become standard practice for treating end-stage liver disease. The success of the procedure relies on effective immunosuppressive medications to control the host's immune response. Despite the liver's inherent capacity to foster tolerance, the early post-transplant period is marked by significant immune reactivity. To ensure favorable outcomes, it is imperative to identify and manage various rejection types, encompassing T-cell-mediated, antibody-mediated, and chronic rejection. However, the approach to prescribing immunosuppressants relies heavily on clinical judgment rather than evidence-based criteria. Given that the majority of patients will require lifelong immuno suppression as the mechanisms underlying operational tolerance are still being investigated, healthcare providers must possess an understanding of immune responses, rejection mechanisms, and the pathways targeted by immunosuppressive drugs. This knowledge enables customization of treatments and improved patient care, even though a consensus on an optimal immunosuppressive regimen remains elusive.

Long-term outcomes of emergency ABO-incompatible living donor liver transplantation using a modified desensitization protocol for highly sensitized patients with acute liver failure: A case report

Although there is no established desensitization protocol for liver transplantation (LT), desensitization usually entails treatment with rituximab, plasmapheresis, splenectomy, and intravenous immunoglobulin (IVIG) infusion together with a local graft. The desensitization protocol is usually initiated 2 to 3 weeks before transplantation. Therefore, patients with acute liver failure warranting urgent LT are usually ineligible for ABO-incompatible (ABOi) LT. For these reasons, several attempts have been made to abridge the desensitization protocol and extend the indication for ABOi living donor LT (LDLT). Here we report a 40-year-old female diagnosed with chronic hepatitis B and acute-on-chronic liver failure (model for end-stage liver disease score, 31). In the absence of a suitable compatible liver donor, emergency ABOi LT was planned using a modified desensitization protocol. The preoperative isoagglutinin (IA) titer was 1 : 1,024 and the preoperative T- and B-cell cross-matches were positive. The patient received a single dose of rituximab (375 mg/m²) and IVIG (0.8 g/kg) was administered from the anhepatic phase until three days after transplantation. Although the patient developed acute cellular rejection in the early stages after LT, she has maintained a stable graft function, even after 5 years. In summary, a modified desensitization protocol consisting of rituximab and IVIG is a feasible strategy for highly sensitized patients with elevated IA titers indicated for urgent LDLT.

ABO-Incompatible Living Donor Liver Transplant From a Blood Type A2 Donor to a Type B Recipient: A Note of Caution

Standardization of immunomodulation protocols has enabled ABO-incompatible liver transplants with outcomes similar to those of ABO-compatible liver transplants. Patients with the A2 blood group are unique because they have a diminished expression of the A antigen. Despite rare immune complications, this phenomenon of diminished expression has led to treatment of type A2 donors according to the regimen for type O blood group donors in ABO-incompatible liver transplants. Additionally, the requirement for pretransplant recipient immunomodulation is consi dered minimal when considering these donors. The transplant of a type A2 donor kidney to a type B recipient is well recognized; however, for liver donation the A2-to-B transplant is rare. Here, we present a case of 48-year-old male patient with blood group type B who underwent ABO-incompatible liver transplant of a right lobe liver graft from a type A2 donor. Postoperatively, despite adequate immunosuppression and initiation of thera - peutic plasma exchange, the patient developed severe and refractory antibody-mediated rejection that ultimately abated with a splenectomy. This report highlights the low but tangible risk of antibody-mediated rejection in ABO-incompatible liver transp lants from type A2 donors and emphasizes the importance of serial monitoring of anti-A isohemag glutinin titers and posttransplant splenectomy to ensure that liver grafts with antibody-mediated rejection can be rescued.

Successful ABO-incompatible living donor liver transplantation using splenectomy and intravenous immunoglobulin in high isoagglutinin titer patients

The role of the isoagglutinin (IA) titer in liver transplantation (LT) is still not well defined, but the general belief is that a higher titer may result in a higher risk of rejection in ABO-incompatible living donor LT. To reduce the IA titer by 1:16 or lower, plasmapheresis is usually performed before transplantation. However, there is no established protocol for patients for whom plasmapheresis has failed before reaching the target IA titers. Here, we report the cases of three patients who show high baseline IA titers and have failed plasmapheresis: no-response to plasmapheresis, allergic reaction associated with plasmapheresis, and anaphylactic reaction to platelet transfusion. For various reasons, after several plasmapheresis procedures, IA titers were not effectively reduced. In these patients, splenectomy and intravenous immunoglobulin (0.8 g/kg, from the anhepatic phase to 2 days after transplantation) were carried. The protocol biopsy on postoperative day 7 showed no histologic evidence of meaningful acute rejection. The main aim of this work is to demonstrate that we can apply this protocol to patients who have high baseline IA titers and have failed plasmapheresis. Furthermore, this report is enhanced to promote to the transplant community this approach with this type of recipient.