Poster Presentation 24th Annual Lorne Proteomics Symposium 2019

Peptides and Penicillins: Identifying the immunogenic β-lactam ligand(s) (#102)

Shawn Goh 1 , Patricia Illing 1 , Nicole Mifsud 1 , Katherine Scull 1 , Robert Puy 2 , Robyn O'Hehir 2 , Anthony Purcell 1
  1. Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
  2. Department of Allergy, Immunology and Respiratory Medicine, Monash University, Central Clinical School, The Alfred Hospital, Melbourne, VIC, Australia

Penicillin hypersensitivity is recognised as a major public health concern with up to 11.5% of recipients reporting adverse reactions. Traditionally, penicillin allergies have been considered to be primarily IgE-mediated, however, there is emerging evidence for a key role for T cell-mediated reactions. Possessing the ability to form covalent bonds (known as haptenation) with serum proteins, penicillins create neo-antigens that have the potential to be immunogenic. Upon processing and presentation by antigen-presenting cells, these haptenated neo-antigens may activate drug-responsive T cells, leading to a range of cutaneous adverse drug reactions from mild rashes to more severe pathologies involving organ damage such as drug-induced liver injury. A group of 10 patients were recruited from The Alfred Hospital Allergy Clinic based on their history of adverse drug reaction to penicillins. Of these patients, only 40% tested positive for serum IgE against the causative drug, suggesting that other factors/cellular populations (i.e. T cells) contribute to the adverse reaction. Here we focus on one hypersensitive patient, who exhibited drug-responsive T cells activated via the human leukocyte antigen (HLA) class-I molecule HLA-A*02:01. We hypothesised that this common Caucasian HLA allotype presented a haptenated neo-antigen to T cells responsible for the ensuing drug reaction. Using an immunopurification LC-MS/MS workflow, we explored the HLA-A*02:01 immunopeptidome isolated from patient-derived B-cells treated with or without penicillin. Utilising haptenated human serum albumin, we defined a set of robust criteria for identification of penicillin-haptenated peptides, which when applied to this data set showed evidence for three HLA-A*02:01 bound penicillin-haptenated peptides. Together, these results set the basis for further characterisation of haptenated peptides in other HLA-A*02:01+ penicillin hypersensitive patients and will provide novel molecular insights into this common drug reaction.