Abacavir inhibits but does not cause self-reactivity to HLA-B*57:01-restricted EBV specific T cell receptors

Abstract

Pre-existing pathogen-specific memory T cell responses can contribute to multiple adverse outcomes including autoimmunity and drug hypersensitivity. How the specificity of the T cell receptor (TCR) is subverted or seconded in many of these diseases remains unclear. Here, we apply abacavir hypersensitivity (AHS) as a model to address this question because the disease is linked to memory T cell responses and the HLA risk allele, HLA-B*57:01, and the initiating insult, abacavir, are known. To investigate the role of pathogen-specific TCR specificity in mediating AHS we performed a genome-wide screen for HLA-B*57:01 restricted T cell responses to Epstein-Barr virus (EBV), one of the most prevalent human pathogens. T cell epitope mapping revealed HLA-B*57:01 restricted responses to 17 EBV open reading frames and identified an epitope encoded by EBNA3C. Using these data, we cloned the dominant TCR for EBNA3C and a previously defined epitope within EBNA3B. TCR specificity to each epitope was confirmed, however, cloned TCRs did not cross-react with abacavir plus self-peptide. Nevertheless, abacavir inhibited TCR interactions with their cognate ligands, demonstrating that TCR specificity may be subverted by a drug molecule. These results provide an experimental road map for future studies addressing the heterologous immune responses of TCRs including T cell mediated adverse drug reactions.

A luminescence-based method to assess antigen presentation and antigen-specific T cell responses for in vitro screening of immunomodulatory checkpoints and therapeutics

“…Finally, this method has potential as a predictive tool for MHC-dependent “off-target” effects in drug development, as previously described ( 14 ) or for early detection and management of immune-related adverse events (irAEs) in combination with bioluminescence imaging (BLI) ( 52 ). As E7-TCR Jurkat would produce luciferase upon antigen-specific activation, real-time, spatial information on T-cell infiltration, persistence, and anti-tumor activity in visceral organ sides may be obtained ( 53 , 54 ).…”

“…Therefore, the study of antigen-specific TCR-mediated responses in the context of the immunosuppressive tumor microenvironment (TME) and checkpoint inhibition, within both adaptive and innate immunity, may be of great importance to optimize and develop novel immunotherapeutic approaches. Antigen-specific Jurkat reporter cells could be implemented in the screening of the effects of therapeutics [as previously described ( 14 )], but also to assess the effect of specific molecules overexpressed within the TME on antigen-specific TCR recognition. Overall, the generation of an antigen-specific Jurkat reporter system expressing an antigen-specific TCR against an easily available cognate antigen is a potentially useful “universal” tool to monitor immunomodulation in an antigen-specific manner in several areas of the immune-oncology field.…”

“…In contrast to fluorescence, which relies on photons as energy source, bioluminescence is derived from naturally catalyzed processes and can have increased assay sensitivities compared to fluorescence assays (11). In particular, luciferase (luc) activity under the NFAT transcription factor promoter (NFAT-luc) has been incorporated into different Jurkat systems to functionally validate and/or identify novel antigen-specific TCRs (12)(13)(14). For instance, a Jurkat NFAT reporter cell line expressing melanoma-specific TCRs was reported to trigger antigen-specific luminescence, allowing for the identification of novel tumor antigens and functional evaluation of cloned TCRs, a crucial task in the development of TCR-based therapies.…”

HLA-B*57:01 Complexed to a CD8 T-Cell Epitope from the HSV-2 ICP22 Protein Binds NK and T Cells through KIR3DL1

“…This could lead to the formation of neo-epitopes that had not participated in negative selection in the thymus and, thus, auto-reactivity. Abacavir binding can also cause the loss of CD8 T-cell responses to pathogens, as recently observed for a HLA-B*57:01-restricted epitope from the gamma-herpesvirus Epstein–Barr virus (EBV) [ 8 ]. A similar observation has been made for the antibiotic flucloxacillin, which also generates hypersensitivity reactions related to CD8 T cells, albeit by a mechanism that appears to increase self protein-derived neo-epitopes by modifying lysine residues within peptide sequences [ 44 ].…”

“…The effect is dependent on the properties of the peptide C-terminus, whereby peptides ending with small hydrophobic residues, such as isoleucine, leucine, and valine, potentially become neo-epitopes in the presence of abacavir. Peptides ending in large hydrophobic residues, such as phenylalanine or tryptophan, may also lose binding, and, as a consequence, the recognition of pathogen peptides may be reduced [ 7 , 8 ].…”