High Throughput T Cell Receptor Sequencing Identifies Clonally Expanded CD8+ T Cell Populations in Alopecia Areata

The study utilized high throughput T cell receptor (TCR) sequencing to investigate the role of CD8+ T cells in Alopecia Areata (AA), an autoimmune disease targeting hair follicles. In both the C3H/HeJ mouse model and human AA patients, researchers identified clonal expansions of CD8+ T cells in lesional skin, suggesting an antigen-driven response. The study found that these pathogenic T cells were also present in skin-draining lymph nodes. Treatment with the JAK-inhibitor tofacitinib in AA patients reduced the number of these expanded T cell clones in the scalp, but many did not completely disappear from the skin or blood, potentially explaining disease relapse after stopping treatment.