Dados do Trabalho

Título

EXPANDING THE HORIZON TO FIND THE UNCHARTED: USING THE EXTENDED SAB PANEL TO IMPROVE HLA ANTIBODY ASSIGNMENT AND IDENTIFY NEW EPLET IN A KIDNEY TRANSPLANTED PATIENT.

Introdução

A 39 years-old, blood group A, male received his first renal transplant from his father in February 2012. He was re-listed on the deceased donor waitlist in December 2015.

Relato do Caso

Patient’s HLA antibody profile was assessed by the single antigen bead (SAB) assay (LABScreen™ Single Antigen, One Lambda Inc) and his predicted two field resolution HLA typing, HLA-A*02:01,*03:01; B*07:02,*44:03; C*07:02,*16:01; DRB1*07:01,*11:01, was based on rSSO (LabType™ SSO, One Lambda Inc) typing results. His father’s HLA typing revealed the following mismatches: HLA-A*01, B*27, C*02 and DRB1*13.

Resultados

HLA-A and -B locus specific pattern of reactivity could be explained by a combination of 7 eplets, while HLA-C locus specific reactivity did not fit any eplet pattern in the epitope registry. Interestingly, serum testing with the extended SAB panel (LABScreen™ Single Antigen ExPlex HLA class I, One Lambda Inc.) identified additional HLA-C allele specificities including HLA-C*16:02 and HLA-C*02:10. Sequence alignment of HLA-C specificities identified using the standard and extended SAB panels identified three nucleotide positions that were likely responsible for the observed HLA-C locus specific antibody reactivity, 73T77N80K.
HLA antibody workup performed in this study, including the ExPlex SAB panel testing, led to the identification of an additional unacceptable antibody targeting HLA-C*16:02 allele, and helped characterize a new 73TNK eplet that is not described in the current version of the HLA epitope registry.

Discussão e Conclusões

This case demonstrates that using additional testing and analysis methods, such as extended SAB panels and sequence alignments, is essential to characterize the true antibody reactivity found in the SAB assay.

Palavras Chave

HLA antibodies, Single-antigen bead assays, Adsorption-elution