Flow cytometric measurement of ABO antibodies in ABO-incompatible living donor kidney transplantation.

Due to different detection methods, a comparison of anti-A/B antibody (Ab) levels among transplantation centers after living donor ABO-incompatible kidney transplantation is problematic. In the present study, anti-A/B Ab levels were determined prior to, and after, blood group A-to-O kidney transplantation using a recently established semiquantitative flow cytometry-based method, ABO fluorescence-activated cell sorting (ABO-FACS), and compared with standard agglutination titers and indirect antiglobulin testing. Pretransplant agglutination titers were reduced from 1:64 to 1:4, by a total of 14 Glycosorb A column immunoadsorptions (IADSs). Compared with the agglutination titers, antidonor immunoglobulin (Ig) M ABO-FACS mean fluorescence intensity ratios (MFIRs) decreased faster and remained low. No difference was observed using donor type or third-party A red blood cells (RBCs) for the ABO-FACS. Glycosorb A columns were not specific, also reducing anti-B and antiporcine IgM levels, which was confirmed by detecting anti-A/B and antiporcine Abs in the column eluates. In conclusion, analysis of pre- and posttransplant Abs from ABO-incompatible kidney transplant recipients by ABO-FACS allows a better understanding of Ab kinetics, which may improve the design of future IADS protocols.