Alopecia areata (AA) is a chronic autoimmune disease leading to recurrent hair loss. NKG2D+ CD8+ T cells are pathogenic, indispensable cells for the development of AA in mouse model, but the role in human AA remains elusive. Recent studies identified systemic inflammation of AA from blood. Some studies reported increased different subsets expressing NKG2D in peripheral blood of patients with AA (i.e. NKG2D+ CD4+, CD8 T cells or CD56+ NK cells), but their clinical implication need to be further studied. Herein, we tried to profile cellular subsets expressing NKG2D using flow cytometry and unbiased approach in blood of AA and healthy volunteers. For the profiling of cellular subset. Anti-CD3, CD4, CD8, CD16, CD56, and anti-NKG2D(CD314) antibodies were used. General composition of lymphoid lineages including CD8, CD4, NK and NKT cells did not show difference between AA and healthy control. Sorted NKG2D+ cells consist of CD3+CD8+ T cells, CD3-CD56+ NK cells, CD3+CD56+ NKT cells in order of abundance and a minor subset of CD3+CD4+ T cells. The NKG2D+ percentage among each lymphoid cells showed that NKG2D+CD8+/CD8 (94.9 vs 93.0%), NKG2D+NK/NK (91.5 vs 87.3%) were slightly increased in AA compared to control. Proportion of NKG2D+ cells among viable PBMC were slightly increased in total NKG2D+ cells (36.1 vs 34.2%), NKG2D+CD8+ (17.4 vs 15.8%) and NKG2D+NK cells (10.1 vs 8.7%) compared with healthy controls, but neither showed statistically significant difference. To understand the relationship between immune subsets and clinical characteristics, we have evaluated the SALT score and activity of AA. But, most of parameters did not show strong correlation with activity nor severity in a small number of our cohorts. NKG2D+ NK cells were increased in severely progressing AA patients with high activity, but no statistical difference was identified. Thus, considering inter-person variation, unbiased comparison between peripheral blood in ‘active’ and ‘stable’ status of AA might be the appropriate to define disease-relevant immune subsets.

LB029 - Subset analysis of NKG2D+ cells in peripheral blood mononuclear cells in alopecia areata

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