FIGURE 1. Reduced DTH reactivity in Dcn^−/− mice compared to wild-type mice.

Left ears of male wild-type and Dcn^−/− mice were challenged with oxazolone. Right ears were treated with vehicle alone. (A) Swelling of the left ears is expressed in µm as the increase of baseline thickness of control ears. Dcn^−/− ears are shown in red and wild-type in black. Dcn^−/− mice show significant less swelling at 24 hours after challenge (*** P < 0.001; n=45 (24 hours); n=30 (48 hours); n=15 (72 hours). Data are expressed as mean ± SEM. (B) To visualize the reduced DTH reaction in three dimensions, combined PET/CT scans were performed 24 hours after challenging to allow detection of maximal differences in metabolic activity between Dcn^−/− and control animals. Arrows indicate the areas of interest in the horizontal and arrowheads in the transaxial image. (C) Quantification of [¹⁸F]-FDG-uptake of the treated ears showed a significant reduction in metabolic activity in the Dcn^−/− mice (n=9; 0.85 ± 0.35 Δ%ID/mL) compared to wild-type (n=9, 1.53±0.58 Δ%ID/mL, P = 0.008). Data are expressed as mean ± SEM. (D–G) Histological examination of oxazolone induced DTH in the ears of wild-type and Dcn^−/− mice. (D) Quantification of infiltrated leukocytes in ear tissue (*** P < 0.001, n=5 ears and 100 sections were quantified) shows reduced infiltration in Dcn^−/− ears. (E) Representative histology (H&E-staining) of wild-type and Dcn^−/− ear section after 24 hours DTH. Bar = 50 µm. Dcn^−/− ears have less leukocytes 24 hours after treatment compared to wild-type ears. The right panels show representative H&E-stainings of untreated wild-type and Dcn^−/− ears. Bar = 200 µm. (F) Quantification of leukocytes in blood vessels over the DTH experiments reveals more leukocytes in Dcn^−/− mice 24 hours after challenging. (D) (P < 0.001 n=5). Bar =50 µm). Data are expressed in mean ± SEM, (G) Representative histology (H&E-staining) of wild-type and Dcn^−/− blood vessels in ear sections after 24 hours DTH. Bar = 50 µm.