Role of IL-17A in reduced NK cell cytotoxicity in eczematous mice. (A) mRNA expression of IL-17A and Th17-related cytokines was analyzed by real-time PCR (spleen) or semiquantitative RT-PCR analysis (skin and draining lymph node). Values were normalized against those of normal mice. Shown are results representative of two independent experiments (n = 4–6 mice). *, P < 0.05; and **, P < 0.01 by the Student's t test. (B) CD3⁺CD4⁺IL-17⁺ Th17 cells were enumerated in draining lymph nodes. (C) The onset of skin lesion development was delayed (left) and the size of primary skin lesions was smaller (right) in mice treated with anti–IL-17 mAb. **, P < 0.01 versus control. (D) NK cells in spleens and lesional skin were enumerated by flow cytometry and immunohistochemistry, respectively. (E) Splenic NK cells expressing granzyme B (GzmB), perforin (Pfn), or IFN-γ were analyzed by flow cytometry in mice treated with anti–IL-17 or control mAb day 2 after infection. (F) Virus titers were measured on day 7. Shown are representative results from three independent experiments. *, P < 0.05; and **, P < 0.01 versus control. (G) Mice were NK-depleted by αAGM1 injection 1 d before VACV infection. Anti–IL-17 antibody was also intraperitoneally injected 2 h after αAGM1 injection. After VACV infection, anti–IL-17 was injected on days 1 and 3, and αAGM1 was injected on days 2 and 5. Skin lesion development was observed and lesion size was measured for 6 d. The result is a representative of two independent experiments. *, P < 0.05; **, P < 0.01; and ***, P < 0.001 versus rat IgG2a–injected mice. #, P < 0.05 versus anti–IL-17 treated, NK-nondepleted mice. Data represent means and SEM values.