Evaluation of the iBeads assay as a tool for identifying class I HLA antibodies.
In addition to antibodies targeting native class I human leukocyte antigens (HLA), the single antigen flow beads assay (SAFB) detects antibodies recognizing denatured forms (anti-dHLA). Acid treated SAFB and the modified SAFB reagent named iBeads are expected to distinguish anti-native (anti-nHLA) from anti-dHLA. Sera from 280 class I HLA-sensitized SAFB-positive kidney transplant candidates were retested with acid-treated SAFB and iBeads. Concordance between SAFB and iBeads, taking into account acid-treatment results, was described at global and locus levels. T-lymphocyte flow cytometry crossmatches (FCXM) were performed to identify an accurate iBeads MFI threshold allowing predicting FCXM results. Concordance between acid-treatment and iBeads assays was observed for 86.9% of alleles. The iBeads MFI were lower than for classical SAFB, especially for HLA-B and C alleles. Anti-dHLA identified with acid-treated SAFB were more frequently negative with iBeads for HLA-B and -C alleles. An iBeads MFI threshold of 1000 allowed predicting positive FCXM with 95.6% sensitivity, 91.6% negative predictive value and 0.08 negative likelihood ratio. The iBeads assay still has limitations, but might represent an invaluable alternative to SAFB for virtual crossmatch strategies in organ transplant allocation programs.
['Visentin|Jonathan|J|', 'Guidicelli|Gwendaline|G|', 'Nong|Thoa|T|', 'Moreau|Jean-François|JF|', 'Merville|Pierre|P|', 'Couzi|Lionel|L|', 'Lee|Jar-How|JH|', 'Taupin|Jean-Luc|JL|']
D000483:Alleles D005260:Female D005434:Flow Cytometry D056426:Genetic Loci D015395:Histocompatibility Antigens Class I D006801:Humans D007159:Immunologic Tests D007518:Isoantibodies D016030:Kidney Transplantation D008297:Male D013601:T-Lymphocytes D014019:Tissue Donors D066027:Transplant Recipients
iBeads HLA antibodies Kidney transplantation Denatured HLA antibodies