Comparison of different luminex single antigen bead kits for memory B cell-derived HLA antibody detection

Abstract

Detection of HLA-specific memory B cells can provide additional information on sensitization of alloantigen-exposed individuals and refine immunological risk assessment. We have recently developed an assay enabling profiling of memory B cell-derived HLA antibodies using luminex single antigen bead (SAB) assay. Here, we compared the performance of the SAB kits from two vendors for memory B cell-derived HLA antibody detection. IgG was isolated from culture supernatants of polyclonally activated B cells from alloantigen-exposed (n = 7) or nonexposed (n = 5) individuals, using our previously established method. Eluates containing isolated IgG from culture supernatants were tested for the presence of HLA antibodies using luminex SAB analysis from both One Lambda and Lifecodes (Immucor). In contrast to Lifecodes, high mean fluorescence intensity (MFI) signals were found for negative control beads in One Lambda (median MFI for class I:1730 and for class II:728), accompanied by high MFI values for self HLA-coated beads, especially for HLA-C. Despite high background in the One Lambda assays, 91% concordance for HLA class I and 85% concordance for HLA class II were found between the specificities detected using SAB kits from the two vendors. Our results show that HLA-specific memory B cells can be profiled using kits from both vendors. However, when analyzing One Lambda results one should be aware of the restrictions related to nonspecific binding particularly in HLA-C-coated beads, and pay attention to self HLA-coated beads in order to accurately identify the reactivities leading to the definition of the actual HLA antibody specificities.

Keywords: bead-based assays; donor-specific antibody; humoral alloimmune response; memory B cells.