Positive Single-Antigen Bead Assay with Negative Flow Crossmatch in a Renal Transplant - A Case Report

• Published in: Indian journal of transplantation Vol. 16; no. 4; pp. 425 - 427
• Main Authors: Mishra, Vikash, Chandra, Dinesh, Anthwal, Archana, Bhardwaj, Amit, Raina, Vimarsh
• Format: Journal Article
• Language: English
• Published: Medknow Publications and Media Pvt. Ltd 01-10-2022; Wolters Kluwer Medknow Publications
• Subjects: Antibodies; denature antigen; donor-specific antibodies; false positive; Histocompatibility antigens; HLA histocompatibility antigens; Kidneys; renal transplant; single-antigen bead; Transplantation; Viral antibodies
• ISSN: 2212-0017; 2212-0025
• DOI: 10.4103/ijot.ijot_73_21

The occasion is when there is discordance between the results of the cell-based and virtual crossmatch and requires further workup before considering a patient for renal transplant. A case of the positive single-antigen bead (SAB) with donor-specific antibodies (DSA) against HLA-A*33:01 with negative complement-dependent cytotoxicity crossmatch and flow crossmatch was identified. The acid treatments of the beads were done to denature the antigen to understand the nature of identified DSA. There was variation in the Mean fluorescence intensity (MFI) observed in between patient sera with acid-treated beads (significantly increased) in contrast to regularly untreated SAB. This indicated additional antigens become available by the denaturation process. Hence, before making a final decision about the transplant in cases of ambiguity, SAB results should be interpreted in light of other compatibility results.