Volume 4 Supplement 3

6th Drug Hypersensitivity Meeting (DHM 6)

Open Access

Abacavir forms novel cross-linking abacavir protein adducts in patients

  • Xiaoli Meng1,
  • Alexandre Lawrenson1,
  • Neil Berry1,
  • James Maggs1,
  • Neil French1,
  • David Back1,
  • Saye Khoo1,
  • Dean Naisbitt1 and
  • Kevin Park1
Clinical and Translational Allergy20144(Suppl 3):P38

DOI: 10.1186/2045-7022-4-S3-P38

Published: 18 July 2014

Background

Abacavir (ABC), a nucleoside-analogue reverse transcriptase inhibitor, is associated with severe hypersensitivity reactions that involve the activation of CD8+ T cells in a HLA-B*57:01-restricted manner. Recent studies have claimed that non-covalent interactions of ABC with HLA-B*57:01 are responsible for the immunological reactions associated with ABC. However, the formation of haemoglobin-ABC aldehyde (ABCA) adducts in patients exposed to ABC suggests that protein conjugation might represent a pathway for antigen formation.

Method

To further characterize protein conjugation reactions, we used mass spectrometric methods to define ABCA modifications of human serum albumin and glutathione S-transferase Pi in vitro and in patients commencing ABC therapy.

Results

ABCA formed a novel intramolecular cross-linking adduct on human serum albumin in patients and in vitro via Michael addition, followed by nucleophilic adduction of the aldehyde with a neighbouring protein nucleophile. Adducts were detected on lysine, histidine, and cysteine residues in subdomain IB of human serum albumin. Only a cysteine adduct and a putative cross-linking adduct were detected on glutathione S-transferase Pi. Modelling the docking of ABCA with HLA B*57:01 confirmed that ABCA has a strong binding affinity when bound covalently to Ser116, a key residue with regards to recognition by ABC-specific CD8+ T cells.

Conclusion

These findings reveal that ABC forms novel types of haptens in all patients taking the drug. It is therefore vital that the immunological consequences of such haptenation pathways are explored in the in vitro models that have been used by various groups to define a new mechanism of drug hypersensitivity for ABC.

Authors’ Affiliations

(1)
Liverpool University, MRC Centre for Drug Safety Science

Copyright

© Meng et al; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Advertisement