Th102 - Friend or Foe? Tissue Resident Memory CD8+ T Cells with Patient Specific TCRs Induce Allopurinol Associated Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Abstract Text: Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) is a rare, T-cell mediated, HLA class I restricted, drug-induced hypersensitivity reaction. SJS/TEN is characterized by keratinocyte death resulting in blistering and sloughing of skin and other mucous membranes. There is currently no established treatment for SJS/TEN other than cessation of causal drug and implementation of supportive care. The gout management medication, allopurinol (ALP), is one of the most common causes of SJS/TEN globally. HLA-B*58:01 is strongly associated with the development of ALP-SJS/TEN; however, the specific mechanisms involved in disease pathogenesis are ill-defined and carriage of the allele is not a complete risk factor. We have therefore established a 10x single-cell-TCR-RNA-CITE-seq pipeline paired with functional approaches in patients with confirmed HLA-B*58:01 restricted ALP-SJS/TEN to identify additional risk factors associated with disease pathogenesis. Single-cell analysis reveals ALP-SJS/TEN blister fluid and affected skin to be heavily infiltrated by CD69+ CD103+ CD8+ TRM T cells expressing patient specific TCRs as well as a mixed population of pro-inflammatory and anti-inflammatory macrophages. Moreover, spatial transcriptomics indicate these cytotoxic CD8+ TRM T cells to be localized to the dermal-epidermal junction in affected skin, suggesting the involvement of cross-reactive viral epitopes in disease pathogenesis. In vitro modeling reveals that some, but not all, patient specific TCRs are activated by drug in the presence of HLA-B*58:01. Together, these findings suggest that other factors, such as specific peptides at sites of tissue damage, may be involved in disease pathogenesis. Further studies could indicate additional risk factors associated with ALP-SJS/TEN and facilitate targeted therapeutic discovery.