(A) Schematic diagram of calcipotriol-plus–5-FU immunotherapy open-label trial. (B) Representative clinical photographs of skin treated with calcipotriol-plus–5-FU. Photographs were taken before (day 0), and after treatment (day 7 and week 8). (C) Representative H&E-stained AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (D) Representative images of CD4/CD8-stained AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. Note that CD4⁺ and CD8⁺ cells are CD3⁺ T cells. (E–H) Quantification of CD4⁺ T cells in AKs (E), CD8⁺ T cells in AKs (F), CD4⁺ T cells in normal skin (G), and CD8⁺ T cells in normal skin (H) before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (I) Representative images of CD4/GATA3-stained AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. Note that GATA3⁺CD4⁺ cells are CD3⁺ T cells. (J and K) Quantification of GATA3⁺CD4⁺ T cells (J) and Foxp3⁺CD4⁺ T cells (K) in AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (L) Representative images of TSLP-stained AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (M) Quantification of TSLP⁺ cells as percentage DAPI⁺ keratinocytes in AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (N) Representative images of ANXA1-stained AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (O–Q) Quantification of ANXA1⁺ cells (O), CALR⁺ cells (P), and HMGB1⁺ cells (Q) as percent DAPI⁺ keratinocytes in AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (R) Representative images of HLA-II–stained AKs before (day 0) and after (day 7) calcipotriol-plus–5-FU treatment. (S) Quantification of HLA-II⁺ cells as percentage DAPI⁺ cells in AKs. Each dot represents an AK or normal skin sample. n = 18 participants at each time point; paired t test. Dashed lines mark the epidermal basement membrane in immunofluorescence images. Scale bars: 100 μm.