Increased and prolonged ear swelling in DTH reactions elicited in VEGF-A transgenic mice. DTH reactions were induced in the ear skin of VEGF-A transgenic and in wild-type mice using oxazolone (A). Ear swelling is expressed as the increase (Δ) over the original ear thickness in μm. Challenged ears in VEGF-A transgenic mice (•) and wild-type mice (▪) showed comparable swelling 24 hours after challenge with oxazolone. Whereas in wild-type mice the swelling reached background levels within 7 days, it was significantly increased and prolonged in VEGF-A transgenic mice. ○ indicates vehicle-treated VEGF-A transgenic mice; □, vehicle-treated wild-type mice. Data are expressed as mean plus or minus standard deviation (SD; n = 5 per condition and time point). After 30 days, inflammation had disappeared in wild-type mice (B). In VEGF-A transgenic mice, the challenged right ears remained erythematous, thickened, and scaly with pronounced vascularization (C). VEGF-A ELISA revealed higher protein concentrations in the noninflamed ears of VEGF-A transgenic mice at 24 hours (D) and 7 days (E) than in wild-type controls. At both time points, VEGF-A levels were increased in the inflamed skin of wild-type mice and were even further elevated in transgenic mice. Data are expressed as mean plus or minus standard error of the mean (SEM; n = 3 per condition and time point). *P < .05; **P < .01; ***P < .001. Taqman quantitative real-time RT-PCR revealed that the mRNA expression levels of the lymphangiogenesis factors VEGF-C and VEGF-D were not up-regulated in the inflamed skin of VEGF-A transgenic mice, as compared with vehicle-treated skin (F,G). Data are expressed as mean plus or minus SD (n = 3 per condition and time point).