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Updated: Mar 16, 2026
Personalized Peptide Arrays for Detection of HLA Alloantibodies in Organ Transplantation
Published on: September 6, 2017
Conformational Variants of the Individual HLA-I Antigens on Luminex Single Antigen Beads Used in Monitoring HLA
Vadim Jucaud1, Mepur H Ravindranath, Paul I Terasaki
11 Terasaki Foundation Laboratory, Los Angeles, CA.
Background:
Single antigen beads (SAB) are used for monitoring HLA antibodies in pretransplant and posttransplant patients despite the discrepancy between virtual and actual crossmatch results and transplant outcomes. This discrepancy can be attributed to the presence of conformational variants of HLA-I on SAB, assessment of which would increase the concordance between SAB and flow cytometry crossmatch (FCXM) results, thus enabling improved organ accessibility for the waiting list patients and a better prediction of antibody-mediated rejection.
Methods:
The conformational variants were examined on HLA-I beads, iBeads, acid-/alkali-treated beads, and T cells using HLA-I monoclonal antibodies (W6/32, TFL-006, and heavy chain (HC)-10).
Results:
The affinity of the monoclonal antibodies against HLA-I beads confirmed the presence and heterogeneous density of peptide-associated β2-microglobulin-associated HLA HC (pepA-β2aHC), peptide-free-β2aHC (pepF-β2aHC), and β2-free HC (β2fHC) on every single antigen-coated bead. In contrast, iBeads harbor a high density of pepA-β2aHC, low density of pepF-β2aHC, and are lacking β2fHC. The FCXM analyses confirmed the prevalence of pepA-β2aHC, but not pepF-β2aHC or β2fHC on resting T cells.
Conclusions:
The strength of a donor-specific antibody should be assessed with a bead-specific mean fluorescence intensity cutoff based on TFL-006 reactivity against HLA-I beads, and HC-10 against iBeads, where the β2fHC or pepF-β2aHC normalized donor-specific antibody level would reveal the true anti-pepA-β2aHC reactivity associated with positive FCXM.
