Figure 3.

Establishment of ultraviolet B (UVB) irradiation protocol. (a) A UVB irradiation protocol was established allowing timing of induction of apoptosis in the basal layer of ear skin, as evidenced by cleaved caspase 3 positivity in the basal layer at day 1 post‐irradiation (top, left panel), gross enlargement of the draining auricular lymph node compared to the contralateral control (top, middle panel), influx of Ly6G⁺ neutrophils into the medulla of the node (top, right panel), expansion of the Lyve‐1⁺ lymphatic network and induction of B cell clusters in the medulla (bottom panel). Images are representative of observations in more than five mice. (b) Quantification of cleaved caspase 3 signal in the basal layer of ear skin. (c) Quantification of BFP signal in the basal layer. For b and c, n = 15 measurements from five mice for the non‐irradiated group and n = 16 measurements from five mice for the irradiated group, pooled from two independent experiments. (d) Quantification of Ly6G⁺ infiltrating cells in the ear, measured in a subset of the samples presented in b and c. (e) Quantification of CD207⁺ Langerhans cells in the ear, for a subset of the samples presented in b and c. In b–e, lines represent mean ± standard error of the mean (s.e.m.). The exact P‐values for two‐tailed Mann–Whitney comparison of non‐irradiated and irradiated groups are given for each of the parameters in their respective graph.