Antibodies and Allograft Outcomes (Videos Available)

Tuesday July 03, 2018 from 09:45 to 11:15

Room: N-117/118

425.4 Unmasking uncertain results after anti-HLA antibody screening in patients on waiting list (Video Available)

David San Segundo, Spain

Immunologist
Immunology
Universitary Hospital Marques de Valdecilla

Abstract

Unmasking Uncertain Results after Anti-HLA Antibody Screening in Patients on Waiting List

Laura Riesco1,2, Juan Irure1,2, Rosa Palomar3, Celestino Piñera3, Emilio Rodrigo3, Marcos López-Hoyos1,2, David San Segundo1,2.

1Immunology, Universitary Hospital Marqués de Valdecilla-IDIVAL, Santander, Spain; 2Tissue Typing Laboratory, Universitary Hospital Marqués de Valdecilla, Santander, Spain; 3Nephrology, Universitary Hospital Marqués de Valdecilla-IDIVAL, Santander, Spain

Introduction: Since the implementation of Luminex for anti-HLA testing, the improvement in the definition of anti-HLA patterns is clear. However, several caveats should be taken into account such as false positive and negative results due to technical issues, denatured molecules, cross-reaction, lack of cut-off consensus, wide inter- and intra-assay variability, prozone effect, interference with complement. The aim of the study is to improve the definition of anti-HLA results after Luminex assay.
Material and Methods: 37 patients were listed in our institution and tested for anti-HLA antibodies both screening and Single Antigen bead (SAB) assays (LABScreen Mixed and LABScreen Single Antigen, One Lambda, CA). Acid treatment of the beads was performed to identify reactions against denatured-HLA (dHLA) or native-HLA (nHLA) molecule and further complement-dependent (CDC) and flow cytometry cross-match (FCXM) tests to confirm dHLA or nHLA reactions.
Results and Discussion: In 21 (57.7%) listed patients, specific reactions with negative screening with SAB Positive results were found. The MFI in the specific reaction was significantly increased in SAB vs screening (4949 ∓ 3030 vs 154 ∓ 87, p<0.001).After acid treatment of the beads, 65% of the reactions against (dHLA) were identified. Moreover, the negative results after CDC and FCXM were confirmed. Performing SAB assay in unsensitized patients in waiting list identify reactions against dHLA molecule without relevance in cross-match.
Conclusion: Acid treatment of the beads allows the identification of dHLA and should be performed to improve the accuracy in anti-HLA antibody assignment.

ISCiiI and FEDER, REDinREN RD16/0009/0027.



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