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BACKGROUND A number of studies have shown the relationship between the pathogenesis of psoriasis and skin resident memory T (TRM) cells. OBJECTIVE To investigate the cytokine profile of TRM cells from skin lesions of psoriasis and the relationship of skin TRM cells to the future clinical course of psoriasis. METHODS We used stocked samples of T cells that were ex vivo expanded from skin biopsies of 10 patients with psoriasis vulgaris. A half of 4-mm punch biopsy specimens was subjected to expansion of skin-infiltrating T cells using IL-2 and anti-CD3/CD28 antibody-coated microbeads. More than 106 T cells per specimen were stocked at -80 °C. Defrosted cells were subjected to flow cytometric analysis. Another half of skin biopsies were subjected to immmunofluorescence staining for CD103 and other markers. RESULTS The biopsied skin revealed CD8+CD103+ TRM cells were present in the epidermis of psoriasis and associated with acanthosis. Sorted CD103+ T cells were mostly CD8+ memory T cells expressing CD69 with a skin-homing potential. A part of CD8+CD103+ T cells produced interferon-γ, IL-17A or IL-22. Notably, CD8+CD103+ TRM cells more frequently produced IL-17A than did CD8+CD103- T cells. We retrospectively divided the 10 cases into the non-advanced therapy group, and the advanced therapy group in which systemic biologics or others were initiated within one year. The frequency of CD8+CD103+IL-17A+ TRM cells tended to be higher in the advanced therapy group. CONCLUSION These results suggest that IL-17A-producing CD8+CD103+ TRM cells are associated with a progressive clinical course of psoriasis.