A Phase II, Prospective, Single-center Study: Correlation of Donor-specific Anti-precursor Endothelial Cells With Transplant Outcome for Recipients of Living-donor Kidney Transplants, Are Auto-antibodies Important.

Antibody Mediated Rejection (AMR) is a major complication of solid organ transplantation. The main reason for AMR is pre-formed, or de-novo, donor specific antibodies against the donor HLA antigens. Additional potential targets are antibodies against MIC-A antigens or antibodies against targets expressed on the donor endothelial cells.

Until recently, no specific means were available to test for the presence of donor-specific endothelial cell antibodies. The newly introduced XM-One AbSorber® assay allows isolating precursor endothelial cells from donor peripheral blood, and thus assessing the presence of donor-specific endothelial cell antibodies.

XM-One AbSorber® is an in-vitro assay that allows for the specific enrichment of precursor endothelial cells which in turn promotes endothelial cells specific cross match testing.

This assay is currently being used in an on-going Northwestern University (NU) research study (STU#00029988). The preliminary results of this study indicate that indeed some of the patients test positive against their respective donors. One potential explanation for this observation, that was not previously entertained, is that the antibodies causing the positive cross match response are actually of autoimmune nature. In order to rule-out such a potential explanation we would like to further test these patients by performing an autologous XM-One AbSorber® assay in which the recipient sera will be incubated with the patients' own cells (as opposed to the respective donor cells in the parental study). This information is crucial for proper analysis of the data obtained in the NU STU#00029988 study.

Initial data from our laboratory indicates that the antigens identified by the XM-One Absorber® assay differ from the HLA antigens usually identified by routine cross match assays. Moreover, we were able to document that this is a polymorphic system and therefore identifying a donor-specific source is critical.