Streamlining ABO antibody titrations for monitoring ABO-incompatible kidney transplants

BACKGROUND: We have monitored ABO antibody titers in 53 ABO-incompatible kidney transplants (INKTs) using a time-consuming, conventional test tube (CTT) method that included a 30-minute room temperature (RT) phase, followed by incubation for 30 minutes at 37°C and conversion to the anti-human globulin (AHG) phase. Our studies have indicated that AHG ABO antibody titers are critical for clinical management, but RT titers do not supplement clinical decision making. Therefore, we assessed AHG titers by two methods: 1) a revised test tube (TT) method without RT and 2) an anti-immunoglobulin G (IgG) gel microcolumn (IgG gel) method with a goal of streamlining ABO antibody titrations. STUDY DESIGN AND METHODS: Fifty frozen samples from our INKT collection with anti-A and/or anti-B AHG titers of 2 to 512 were titrated by revised TT method with 30 minutes at 37°C and conversion to AHG and by IgG gel method with 15 minutes at 37°C and centrifugation. RESULTS: The titers using the revised TT and IgG gel methods had 64 and 52% concordance, respectively, with CTT AHG titers. Neither the revised TT AHG titers nor the IgG gel titers varied by more than one standard dilution from the CTT AHG titers, which is within acceptable limits for titration techniques. CONCLUSIONS: The revised TT and IgG gel titers are comparable to the CTT AHG titers. The IgG gel method offers the best titer turnaround time, eliminating 45 minutes of incubation time alone. Implementation of this technique would benefit ABO INKT patients by providing titer results in a more timely manner.