(A) Graphs showing mean ± SD epidermal accumulation of MataHari T cells following F→M BMT according to the presence or absence of CD207⁺ cells in the host (n = 5–9/group). Timing of DT or PBS treatment determined depletion or otherwise of different subsets of host CD207⁺ populations from the skin (all CD207⁺ n = 7–8/group, LC only n = 8–9/group, or CD207⁺ dDC only n = 5–6/group) in male Langerin.DTR or established (male Langerin.DTR→B6 male) bone marrow chimeras used as BMT recipients. ***P ≤ 0.001 by 2-tailed Mann-Whitney U test. (B) Left: Representative images of immunofluorescence staining of epidermal sheets showing unilateral LC (green) depletion achieved through intradermal injection of DT (left ear, top image) or PBS (right ear, bottom image). Scale bars: 50 μm. Right: Graphs show summary data for mean ± SD of LC numbers (top) and epidermal T_E numbers (bottom) in each ear at day 7 (n = 10). **P ≤ 0.01 by 2-tailed Wilcoxon’s matched-pairs signed-rank test. (C) Evolution of the T_RM phenotype of epidermis-located MataHari T cells in the presence (PBS) or absence (DT) of LCs (left: representative FACS plots of CD69 and CD103 expression over time; right: summary data). *P ≤ 0.05 by 2-tailed Wilcoxon’s rank-sum test. (D) Left: Representative images of H&E staining of skin samples from male Langerin.DTR allo-BMT recipients treated with PBS or DT. Right: Summary data of the histopathologic severity score (lines represent median). **P ≤ 0.01 by Mann-Whitney U test. (E) Survival of F→M BMT recipients according to the presence or absence of LCs (BMT + T cells ± DT, n = 8/group) or BMT no–T cell controls (n = 3). Log-rank Mantel-Cox test. BM, bone marrow; BMT, BM transplantation; dDC, dermal dendritic cell; DT, diphtheria toxin; D+, number of days after BMT; Epi, epidermis; H&E, hematoxylin and eosin; LC, Langerhans cell; T_E, effector T cell; T_RM, resident memory T cell.