title: Evaluation of the iBeads assay as a tool for identifying class I HLA antibodies.
abstract: 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.
authors.affiliation: Laboratoire d'Immunologie et Immunogénétique, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France; UMR CNRS 5164, Université de Bordeaux, Bordeaux, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Visentin
authors.affiliation: Laboratoire d'Immunologie et Immunogénétique, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France.
authors.forename: Gwendaline
authors.initials: G
authors.lastname: Guidicelli
authors.affiliation: One Lambda, Inc., Canoga Park, CA, USA.
authors.forename: Thoa
authors.initials: T
authors.lastname: Nong
authors.affiliation: Laboratoire d'Immunologie et Immunogénétique, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France; UMR CNRS 5164, Université de Bordeaux, Bordeaux, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Moreau
authors.affiliation: UMR CNRS 5164, Université de Bordeaux, Bordeaux, France; Service de Néphrologie, Transplantation, Dialyse, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Merville
authors.affiliation: Service de Néphrologie, Transplantation, Dialyse, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Couzi
authors.affiliation: One Lambda, Inc., Canoga Park, CA, USA.
authors.forename: Jar-How
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Laboratoire d'Immunologie et Immunogénétique, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France; UMR CNRS 5164, Université de Bordeaux, Bordeaux, France. Electronic address: jean-luc.taupin@chu-bordeaux.fr.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Taupin
mesh_terms: D000483:Alleles; D005260:Female; D005434:Flow Cytometry; D056426:Genetic Loci; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007159:Immunologic Tests; D007518:Isoantibodies / Q000276:immunology*; D016030:Kidney Transplantation; D008297:Male; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014019:Tissue Donors; D066027:Transplant Recipients
chemical_list: D015395:Histocompatibility Antigens Class I; D007518:Isoantibodies
keywords: Denatured HLA antibodies; HLA antibodies; Kidney transplantation; iBeads