Identification of antigenic targets for AECAs and the effect of desensitization treatment. (A) Protein array analysis of 14 AECA eluates derived from endothelial cell crossmatch-positive sera. Relative fluorescence units (RFUs) for antibodies specific for EDIL3, endoglin (ENG), ICAM4, and FLT3 Ligand (FLT3LG) were significant compared with the mean signal intensity of low-abundance antibodies. We defined a positive threshold of 2000 RFU as a cutoff for abundance. The error bars represent SEM. (B) Effect of plasmapheresis/intravenous Ig (PP) on AECA levels. AECAs specific for ENG, FLT3LG, EDIL3, and ICAM4 decreased after PP treatments and rebounded in a post-transplant serum that yielded a positive endothelial cell crossmatch test. Data shown are from a single renal recipient, and values were normalized to total IgG. EC, endothelial cell; Txn, transplantation.