P112 Clearance of pre-formed donor specific antibodies after liver transplantation is specific for DSA and cross-reactive antigens

Abstract

Aim Liver transplant recipients with pre-formed HLA DSA are reported to “clear” antibodies post-transplant. We sought to determine if the reduction in HLA antibodies was specific for donor antigens or represented a global decline in alloantibodies. Methods We retrospectively analyzed the post-transplant DSA course for 27 liver allograft recipients transplanted with pre-formed HLA DSA, measured by single antigen assay. Results In 16 patients, DSA was persistently seen at last follow-up (although weaker than pre-transplant in all patients); another 2 patients also developed de novo DSA to other donor HLA. In the remaining 9 patients, DSA declined dramatically post-transplant and was not detected at last follow-up. We asked whether third party antibodies also declined (i.e. global immunosuppression) or whether the patterns were specific for DSA and cross-reactive antigens. In 6 of 9 patients whose DSA declined, some non-DSA remained strong while the third party antibodies that reduced were clearly in cross-reactive groups with the donor specific antibodies. In one of the remaining patients, all of their antibodies disappeared post-transplant, in another the DSA did not fit into a CREG, and in the last patient DSA was to HLA-C locus. One example is given in the figure below, where strong antibodies persisted to third party A1 CREG; but DSA to A32 and antibodies to other A10/A19 CREG antigens declined post-transplant. In the same patient DSA to DQ6 disappeared during follow-up, as did non-DSA DQ5 antibodies; but antibodies to DQ2 persisted. Conclusions Overall, liver allograft recipients experienced a global reduction in HLA antibodies, but the most profound effect was on DSA and CREG-related antigens. These cases suggest that liver clearance of HLA antibodies is specific for donor reactive antibodies and cross-reactive clones.