Impaired CHS with decreased T cell trafficking to a challenged skin site in AQP3-null mice. (a, left) Mice were sensitized with DNFB, TNCB, or Oxa and challenged 5 d later on the ear. The ear thickness was measured in micrometers 24 h after the challenge (SE; n = 5; *, P < 0.01). (right) Hematoxylin and eosin staining of the ears of sensitized WT and AQP3^−/− mice at 24 h after challenge with DNFB. Bars: (left) 100 µm; (right) 20 µm. (b) CHS test using BM cell–transferred mice. C57BL/6 mice received transplants of BM cells from WT and AQP3^−/− mice. The CHS test was performed with DNFB 2 mo later (SE; n = 4; *, P < 0.01). (c) Adoptive transfer experiments by intravenous injection. LN cells from sensitized donor WT and AQP3^−/− mice (Don) were injected intravenously (3 × 10⁷ cells/head) to recipient mice (Rec). Ear swelling at 24 h after challenge (SE; n = 3–5; *, P < 0.01) is shown. (d) Adoptive transfer experiments by intravenous injection. LN cells from sensitized WT and AQP3^−/− donors were stained with CMFDA and injected into recipient WT mice, and these mice were challenged with 0.3% DNFB. The ear skin, which was painted with DNFB, and LNs were excised 24 h after challenge. CD4⁺ and CMDFA⁺ cells were analyzed by flow cytometric analysis (SE; n = 4; *, P < 0.01). (e) Adoptive transfer experiments by subcutaneous injection (2 × 10⁵ cells) into the ears. Ear swelling at 24 h after challenge is shown (SE; n = 4). Experiments in a, c, and e were performed in two other independent experiments and in b and d in one other experiment with similar results.