A2 liver transplantation across the ABO barrier: Increasing options in the donor pool?

Blood Type A1 Mismatch Does Not Affect Heart Transplant Outcomes at One Year

There are subtypes within blood type A, termed non-A1, that have reduced expression of A antigen on cell surfaces. This can result in the development of anti-A1 antibodies. There is limited information regarding the impact of this in heart transplant (HTx) recipients. We conducted a single-center cohort study of 142 Type A HTx recipients in which we compared outcomes of a match group (an A1/O heart into an A1 recipient or a non-A1/O heart into a non-A1 recipient) with a mismatch group (an A1 heart into a non-A1 recipient or a non-A1 heart into an A1 recipient). At one year post-transplant, there were no differences between the groups in survival, freedom from non-fatal major adverse cardiovascular events, freedom from any treated rejection, or freedom from cardiac allograft vasculopathy. There was an increased hospital length of stay in the mismatch group (13.5 vs. 17.1 days, p = 0.04). Our study showed that A1 mismatch was not associated with worse outcomes at one year post-HTx.

Can Living Donor Liver Transplantation in the United States Reach Its Potential?

Living donor liver transplantation (LDLT) is a vital tool to address the growing organ shortage in the United States caused by increasing numbers of patients diagnosed with end-stage liver disease. LDLT still only makes up a very small proportion of all liver transplantations performed each year, but there are many innovations taking place in the field that may increase its acceptance among both transplant programs and patients. These innovations include ways to improve access to LDLT, such as through nondirected donation, paired exchange, transplant chains, transplant of ABO-incompatible donors, and transplants in patients with high Model for End-Stage Liver Disease scores. Surgical innovations, such as laparoscopic donor hepatectomy, robotic hepatectomy, and portal flow modulation, are also increasingly being implemented. Policy changes, including decreasing the financial burden associated with LDLT, may make it a more feasible option for a wider range of patients. Lastly, center-level behavior, such as ensuring surgical expertise and providing culturally competent education, will help toward LDLT expansion. Although it is challenging to know which of these innovations will take hold, we are already seeing LDLT numbers improve within the past 2 years.

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.

Lessons learnt from living donor liver transplantation with ABO-incompatibility: A single-centre experience from southern India

BACKGROUND

Although, ABO-incompatible (ABOi) liver transplantation is considered a high-risk procedure, using newer and more effective preoperative B cell desensitisation techniques, many transplant centres are routinely performing ABOi living donor liver transplantation (LDLT).

METHODS

This was a retrospective study of 12 patients (adult:pediatric = 10:2; M:F = 9:3; median age, 45.5 years [range 1 to 56 years]) who underwent ABOi LDLT at a tertiary care centre.

RESULTS

The median model for end-stage liver disease (MELD)/pediatric end-stage liver disease (PELD) scores were 28 (range 18 to 35) and 30.5 (range 24 to 37), respectively. For desensitisation, we initially used two doses of rituximab and two sessions of plasmapheresis preoperatively. We faced high mortality in the initial seven patients (five deaths) due to overwhelming sepsis from multidrug-resistant (MDR) pathogens. Subsequently, we restricted the rituximab to one dose and performed plasmapheresis only when isoagglutinin titre value was more than 1:64. With this regimen, out of the last five patients, four did well. For the whole cohort, the incidence of antibody-mediated rejection, acute cellular rejection, biliary complications, hepatic artery thrombosis, infection, and 5-year patient survival were 16.7%, 16.7%, 16.7%, 8.3%, 75%, and 40%, respectively. The risk factors for mortality were high MELD score, O blood group, and more intense desensitisation protocol.

CONCLUSIONS

Careful selection of patients and less intense desensitisation protocol are probably important in improving the outcomes in ABOi LDLT.