Detection of Post-Transplant Anti-HLA Donor-Specific Antibodies through the Use of Stored Donors’ Cell Lysates and Solid Phase-Based Cross-Matching

Abstract

Transplant recipients who have sensitizing events such as pregnancies, blood transfusions and previous transplants often develop antibodies directed against human leukocyte antigen (HLA)-molecules of the donors’ organs. These pre-formed donor-specific antibodies (DSA) represent a high risk of organ failure as a consequence of antibody-mediated hyper-acute or acute allograft rejection. In order to select recipients without donor-specific anti- HLA antibodies the complement-dependent cytotoxicity crossmatch assay (CDC-CM) was established as standard procedure more than forty years ago. This assay, however, is characterized by several drawbacks such as a high degree of vitality (at least 90%) required for the target lymphocytes of a given donor. This requirement highly limits its applicability for patients treated with therapeutic antibodies, special drugs or patients who suffer from underlying diseases i.e., especially from type III (immune complex) auto-immune diseases. Furthermore, only DSA which exert complement-fixing activity are detected. As a consequence novel crossmatch procedures which act independently of the complement system and which do not represent functional assays have been generated in the format of flow cytometry (FACS-) or solid phase (ELISA-) assays. Especially solid phase-based assays the outcomes of which are not limited by insufficient cell vitalities have in spite of various environmental disruptive factors been shown to lead to valid results and not to false positive outcomes in contrast to CDC-based cross-matching. Our current results show the superiority of ELISA-based cross-matching in a novel context. Data are provided which show the ELISA-based applicability of long term-stored donors’ materials to demonstrate or exclude the involvement of DSA in a rejection episode by de facto cross-matching and not only by the virtual crossmatch approach i.e., the comparison of the recipients’ anti-HLA antibody specificities with the donors’ historically identified HLA-pheno- and/or genotypes.