ABO-incompatible (ABO-i) kidney transplantation (KT) has emerged for overcoming the shortage of organ donors. Although this technique initially achieved only low graft survival due to isoagglutinin, recently developed desensitization protocols have improved survival to levels that are comparable to ABO-compatible KT. However, isoagglutinin is still regarded as a major obstacle to ABO-i KT. In this study, we evaluate the impact of isoagglutinin titer on clinical outcomes as well as factors that may influence isoagglutinin titers. In total, data from 95 patients who underwent ABO-i KT were analyzed. Preoperatively, rituximab administration and plasmapheresis were performed until the titer was reduced to ≤1:4. Retrospective analysis included blood group; timing and dosage of rituximab; isoagglutinin titer; number of plasmapheresis; and clinical outcomes including graft survival and serum creatinine. Graft survival was 95.8% (n = 91) and average serum creatinine at 1- and 1.5-year post-ABOi-KT was 1.3. Three patients died of sepsis. The identified predictors of titer-rebound after transplant were short interval (<7 days) between rituximab and first plasmapheresis (P = 0.004); high initial titer (≥256) (P = 0.023); low titer-reduction rate (P < 0.001); and blood group O (P < 0.001). One patient who experienced a rebound developed antibody-mediated rejection. With low-dose (200 mg) rituximab, the change in isoagglutinin titer-rebound was not significant and the infection rate was significantly decreased (P = 0.001). In conclusion, isoagglutinin titer-rebound within the first 2 weeks after KT may be a risk factor for rejection. The factors identified as affecting titer-rebound after KT were high initial isoagglutinin titer, low titer-reduction rate, short interval, and blood group O.

BackgroundTo rapidly obtain outpatient results, we use plasma separation tubes (PST) for chemistry analysis. If lactate dehydrogenase measurement is required, serum separation tubes (SST) are used. There has been no evaluation of hemolysis with these tubes. We compared the hemolytic index (HI) obtained by using PST and SST and applied this for choosing appropriate tubes for clinical laboratories.MethodsThe HI of specimens obtained from outpatients visiting Asan Medical Center between July and December 2012 was analyzed. The HI was scored from 0 to 10 by using the Toshiba 200FR (Toshiba Medical Systems Co., Japan). HI was classified by sample tube type, and significant hemolysis was defined as a HI of 2 or more. For significant hemolysis cases, medical records were reviewed to identify the causes.ResultsAmong 171,519 specimens, significant hemolysis was observed in 0.66% of specimens (0.68% of PST specimens, 0.46% of SST specimens). The mean HI in PST was 0.18 (SD: 0.43) and that in SST was 0.14 (SD: 0.37). The proportion of significant hemolysis was significantly higher in PST than in SST (P=0.001). The cause of significant hemolysis was identified as chemotherapy and prosthetic valve in 48.1% of specimens. Complex sampling errors may have caused significant hemolysis in the remaining 51.9% of specimens.ConclusionsThe incidence of hemolysis was slightly higher for PST than SST, although both were <1%. PST are thought to be more useful than SST in outpatient testing because of rapid turnaround time, greater sample volume, and less risk of random errors due to fibrin strands.