Storage-Induced Changes Promote Erythrocyte Recognition by Autoantibodies,

Abstract 3371

Physiological erythrocyte removal is associated with a selective increase in the expression of senescent cell antigens related to band 3, and subsequent autologous antibody binding and phagocytosis. Chronic erythrocyte transfusion often leads to immunization and the formation of alloantibodies and autoantibodies. In order to understand the molecular basis for this phenomenon we investigated whether erythrocyte storage leads to increased expression of non-physiological neoantigens.

Immunoprecipitations were performed with erythrocytes and vesicles from blood bank erythrocyte concentrates of increasing storage periods, using plasma containing erythrocyte autoantibodies from selected patients with autoimmune hemolytic anemia (N=6). Patient plasma autoantibody binding to erythrocytes increased with erythrocyte storage time, while the exact opposite was observed for plasma from healthy volunteers, showing that erythrocyte antigenicity changes during storage. SDS polyacrylamide gel analysis combined with proteomics revealed band 3 to be a dominant target of the autoantibodies. From vesicles that are formed during erythrocyte storage, the autoantibodies precipitated protein complexes distinct from those recognized on erythrocytes, indicating that they have a different immunization potential. Soluble immune mediators including complement factors were present in the patient plasma immunoprecipitates, but not in the control immunoprecipitates.

These findings support the hypothesis that disturbed erythrocyte aging during storage of erythrocyte units contributes to transfusion-induced alloantibody and autoantibody formation.