Low but not absent risk of alloimmunization against RHD in patients receiving RHD-incompatible red blood cells during liver transplantation

Transfusion demand is high in liver transplantation (LT) and thus, RHD-positive red blood cell concentrates (RBCs) are frequently given to RHD-negative patients during LT. It has been suggested that formation of anti-D antibodies is then rare, probably due to immunosuppression, in these patients. We assessed the rate of anti-D formation in RHD-negative patients undergoing LT who were transfused with RHD-positive RBCs.

RHD-type and transfusion history of patients who underwent LT were reviewed retrospectively. In RHD-negative patients, who received RHD-positive RBCs, results of antibody screening test (indirect antiglobuline test and with papain treated RBCs) and direct antiglobulin test as well as medical records were retrospectively evaluated.

527 patients underwent 576 LT within the observation period between 2010 und 2023. 87 patients were RHD-negative, of whom 42 were transfused with RHD-positive RBCs. In 34 of them, an antibody screening test result was available more than 2 after weeks after the last RHD-positive RBC was administered. In two of them, a transient, weak anti-D antibody was detectable. In one of these patients, anti-D was also detectable after elution, without overt signs of hemolysis. In both patients, anti-D disappeared rapidly in the further course.

Transient anti-D occurred in a minority of RHD-negative patients undergoing LT after transfusion of RHD-positive RBCs. The evidence of a primary immune response was low. To save stocks of RHD-negative RBCs, transfusion of RHD-positive RBCs to RHD-negative patients during LT can be considered as relatively safe probably due to immunosuppression but should be limited to men and women beyond the childbearing age as precautionary measure.

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