METHODS: Single cell technologies including T-cell receptor αβ sequencing, multi-parameter flow cytometry, full transcriptome RNA-seq, and mass cytometry were used to define the clonality and molecular signatures of pathogenic drug-specific T cells from paired PBMC, blister fluid, and acute, recovery, and patch test positive skin in SJS/TEN and AHS (n=25).
RESULTS: Dominant CD8+ T-cell clonotypes of effector memory phenotype (CCR7-) with variable expression of skin homing/residence markers (CLA, CD103) were seen in SJS/TEN skin and blister fluid and were present at much lower frequency in both acute and drug-stimulated recovery peripheral blood. A public TCR was dominant in blister fluid of HLA-B*15:02 restricted carbamazepine-SJS/TEN. For allopurinol SJS/TEN, a dominant clonotype was identified in HLA-B*58:01+ blister fluid and a novel HLA class I restriction was identified with striking T-cell clonality (>97%) in blister fluid and skin. In contrast, for AHS, abacavir responsive CD8+ T cells with shared TCR clonotypes were isolated from the peripheral blood and positive patch tests that were polyclonal.
CONCLUSIONS: Single cell approaches that define the signatures of drug-specific T cells in the skin and peripheral blood highlight mechanistic differences between HLA class I restricted drug hypersensitivity syndromes and will help drive the development of targeted therapeutics and screening approaches.