166-P: IDENTIFICATION OF A NEW HLA-B27 ALLELE

Abstract

Aim A 54 year old male patient was referred to tissue typing lab to confirm a questionable HLA-B27 typing identified by flow cytometry. Methods HLA typing was performed by serology (GTI and Biorad), Luminex SSO (Thermofisher), high-resolution SSP (Olerup & Thermofisher), and SBT (Life Technologies). DNA cloning and sequencing was also conducted. Results Medium resolution SSO typing revealed the patient is B∗27:61 and B∗35. Serology typing confirmed expression of B27 with strength of 6-8. High-Res SSP on B27 tray showed as B∗27:23 but not B27∗61. SBT analysis confirmed its similarity to B∗27:61 with a G/T mutation at position 292 in exon 2, which results in a change of aspartic acid to tyrosine at codon 74. Finally, the new B27 allele was cloned for regions starting from intron 2 till the beginning of exon 5. BLAST search against IMGT 3.11 database confirmed the novelty of the allele.[figure1] Conclusions We have identified a new HLA-B27 allele with an amino acid mutation at the antigen recognition site. The new allele could potentially alter the peptide repertoire being presented to CD8+ T cells. Its association with diseases, such as ankylosing spondylitis, remains to be determined.