A) Skin CHS to DNCB by ear thickness increase in WT and NK1RKO B6 mice. B) Microscopic images of the ears of mice in (A) showing epidermal-dermal thickness (lines), hyperkeratosis, parakeratosis, acanthosis and leukocyte inflammatory infiltrate. C) Skin CHS to DNCB, in WT, Tac1KO, Tac4KO and Tac1/Tac4KO B6 mice. D) Representative microscopic images of mouse ears in (C). E) CHS to DNCB in Tac1/Tac4KO B6 mice injected i.d. with SP or HK1, or SP and HK1 during sensitization. F) Microscopic images of the ears of mice in (E) showing epidermal-dermal thickness (lines) and leukocyte infiltrate. In (A), (C) and (E), representative experiment of 3. (A) Six mice per group, (B) and (C) 5 mice per group. Means ± 1 SD analyzed by 1-way ANOVA followed by Student-Newman-Keuls test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. NS: not significant. Statistic comparisons among values obtained 48 h following ear skin elicitation are depicted. In (B), (D) and (F), images are from samples obtained 48 h after elicitation. H&E, X200, scale bars, 20μm.