Performance and Advancement of the Kidney Solid Organ Response Test.

BACKGROUND: The kidney solid organ response test (kSORT) has been investigated for the prediction of acute rejection in kidney transplant recipients with conflicting results. We aimed to investigate if the kSORT assay score is associated with rejection or immune quiescence. METHODS: The blinded association between rejection and kSORT > 9 were investigated. Optimization of kSORT prediction was evaluated after unblinding to determine the optimal prediction cutoff value of kSORT score. Additionally, the predictive capability of the kSORT gene set was assessed using blinded normalized gene expression data from microarray (Affymetrix) and qPCR assays. RESULTS: Of the 95 blood samples analyzed, 18 patients had blood samples before transplant, 77 patients after transplant and 71 had clinically indicated biopsies of which 15 biopsies showed acute rejection and 16 showed chronic active antibody-mediated rejection. When 31 patients with rejection were compared to the remaining 64 patients, positive predictive value (PPV) was 54.29% and negative predictive value (NPV) was 75% when stratified using a kSORT score > 9, and PPV was 57.89% and NPV was 78.95% when stratified using a kSORT score > 5. Using the kSORT assay for detection of rejection showed an area under the curve value of 0.71. Microarray data improved prediction accuracy with PPV of 53% and NPV of 84% compared to qPCR results (PPV and NPV were 36% and 66%), respectively. CONCLUSIONS: The kSORT assay has the potential to be used as a predictive tool for active rejection and/or immune quiescence, but additional studies will be useful in improving and refining the kSORT assay, in particular the prediction algorithm.

Hybrid glycophorin and red blood cell antigen genotyping in Asian American type O blood donors with Mia phenotype.

BACKGROUND: The GP.Mur glycophorin with Mia phenotype is relatively common and clinically significant in the Southeast Asian populations. The aim of this study is to genotype Mia -positive Asian American type O blood donors. Red blood cell (RBC) minor antigens were also determined in the same cohort. STUDY DESIGN AND METHODS: Asian American blood donors of the Gulf Coast Regional Blood Center (Houston, TX) were screened using a typing reagent (NOVACLONE Anti-Mia Monoclonal IgG Typing Reagent, Dominion Biologicals Ltd) from March 2016 to July 2018. Aliquots of Mia -positive blood from type O donors were subjected to serologic confirmation using Mia - and/or Mur-specific GAMA210 and 64D6 monoclonal antibodies, and two human antisera. Extracted genomic DNA was amplified by polymerase chain reaction (PCR) using GYP hybrid gene/allele-specific primers followed by bidirectional Sanger sequencing. Zygosity for GYP*Mur and GYP*Bun was determined using TaqMan real-time PCR assay. Phenotypes of 35 RBC antigens and three phenotypic variants were determined with use of an in vitro diagnostic test, PreciseType HEA Molecular BeadChip Test (Immucor). RESULTS: By screening 4600 blood donations in the Houston metropolitan area, 209 samples from 103 unique donors were identified to be Mia -positive. By PCR and sequencing analysis, 97 of the 103 Mia -positive donors carried hybrid genes GYP*Mur (89.7% including two homozygotes), GYP*Bun (6.2%), GYP*Vw (3.1%) and GYP*Hut (1.0%). Concordance between serology and DNA analysis was 98%, 99%, and 100% for the GAMA210, 64D6, and human antisera, respectively. Genotyping of RBC antigens showed that the Mia -positive donors were predominantly associated M+ N- S- s+ (48.5%) and M+ N+ S- s+ (38.1%) phenotypes. CONCLUSIONS: The GP.Mur glycophorin is most prevalent in the Mia -positive Asian American type O blood donors.