Hyperacute rejection of living related kidney grafts caused by endothelial cell-specific antibodies: case reports.

We describe two cases of hyperacute humoral rejection of living related kidney grafts despite negative pretransplantation T- and B-lymphocyte flow cytometric crossmatches and blood group identity. Retrospectively, antiendothelial IgG antibodies were detected on a panel of umbilical cord cells in the first case, and IgM antibodies against donor endothelial precursor cells were detected using a new endothelial cell crossmatch kit in the second case. Standard crossmatch methods using donor lymphocytes failed to detect these pathogenic antibodies and did not predict the danger of hyperacute rejection.