Who Says AMR Doesn’t Happen in Liver Transplant Patients?

Key Points

• The podcast episode challenges the long-held belief that the liver is completely resistant to antibody-mediated rejection (AMR) following transplantation.
• Dr. Jacqueline O'Leary explains that while the liver is more resistant due to its size, regenerative capacity, and other factors, it is not immune to AMR, with established criteria for acute AMR and proposed criteria for chronic AMR.
• A key distinction is made between Class I antibodies (associated with early, high-titer acute AMR) and Class II antibodies (linked to chronic rejection and late graft injury).
• Significant barriers to addressing AMR in liver transplants include a lack of standardized antibody testing protocols, cost concerns, and a generational knowledge gap among clinicians who received no training on the subject.
• The discussion advocates for pre- and post-transplant HLA antibody screening, protocol biopsies, and the use of non-invasive tools like FibroScan to personalize immunosuppression and improve patient outcomes.
• A major proposed solution is enhanced education for GI and hepatology fellows on HLA and AMR to foster better collaboration between clinical teams and HLA laboratories.

Summary

This episode of the "Coffee and Compatibility" podcast features a discussion with Dr. Jacqueline O'Leary, a hepatology expert, on the controversial topic of antibody-mediated rejection (AMR) in liver transplantation. The conversation begins by addressing the historical perception that the liver is uniquely resistant to AMR, a view Dr. O'Leary's foundational work has helped to challenge. She explains that the liver's size, regenerative ability, secretion of soluble Class I antigen, and lack of constitutive Class II expression contribute to its relative resistance, but do not make it immune. Definitive criteria for acute AMR now exist, and work is ongoing to refine criteria for chronic AMR.

A critical insight from the discussion is the differential impact of antibody types: high-titer, multiple Class I antibodies are associated with early acute AMR and graft loss, while Class II antibodies are more implicated in chronic rejection and late graft injury. However, a significant obstacle is the lack of standardized, cost-effective testing protocols and established cut-off values for antibody levels that constitute a real risk.

The dialogue identifies a major barrier to progress as a generational and educational gap. Many experienced hepatologists and surgeons, having practiced for years without considering AMR, often dismiss its relevance. This is compounded by a complete lack of formal training on HLA and AMR in GI and transplant hepatology fellowships, leaving new clinicians unprepared to interpret HLA lab data. To shift this mindset, Dr. O'Leary strongly advocates for routine pre-transplant antibody screening and post-transplant monitoring, including protocol biopsies and DSA testing, paired with non-invasive tools like FibroScan. This data-driven approach allows for the personalization of immunosuppression, enabling safe reduction to very low levels in stable patients while identifying those at risk.

The episode concludes by emphasizing the necessity of cross-disciplinary education. Empowering fellows and clinicians with knowledge about HLA sensitization risks (e.g., from transfusions) and the role of antibodies as biomarkers will foster better collaboration between HLA laboratories and clinical teams. This, in turn, is essential for implementing personalized medicine strategies that can ultimately improve long-term outcomes for liver transplant recipients.