Characterising the challenges of managing difficult red blood cell alloantibodies in liver transplant recipients.

Aims: Formation of red blood cell alloantibodies (RBCAs) complicates transfusion support in liver transplantation (LT). Difficult RBCAs (DAs, >3 antibodies or antibodies for which <25% donors are antigen negative) further challenge care. This study characterises DA outcomes relative to non-difficult RBCAs (NDAs).

Methods: Single-centre, retrospective analysis of LT patients (2002-2021). RBCAs were defined as clinically significant antibodies. DAs were compared with NDAs.

Results: 89 patients had clinically significant RBCAs (DA=50, NDA=39). More DAs were anti-Jka, anti-M; fewer were anti-E, anti-K (all p<0.05). DA patients often had multiple antibodies (44% vs 12.8% NDA, p=0.0022). Probability of finding antigen-negative blood was lower for DAs (17.4% vs 68.1% NDA, p<0.0001) as was RBCs received (9.4 vs 14.7 units in NDA, p=0.0036). Although survival was similar, patients with DAs had more adverse reactions (8% vs 0%, p=0.128). Some antibodies appeared to occur with specific liver diseases (such as primary sclerosing cholangitis, alcoholic steatohepatitis and recurrent disease); however, due to low sample size, definitive conclusions cannot be made.

Conclusions: DA LT recipients contain >1 RBCA, have a lower probability of finding antigen negative blood and may experience more adverse transfusion event (ATE). Despite this, the incidence of ATEs was still quite low.