Characterization of allergic response induced by repeated dermal exposure of IL-4/Luc/CNS-1 transgenic mice to low dose formaldehyde

Although formaldehyde (FA) is known to be a major allergen responsible for allergic contact dermatitis, there are conflicting reports regarding correlation between FA exposure and interleukin (IL-4) expression. To investigate whether allergic responses including IL-4 expression were induced by repeated dermal exposure to low dose FA, alterations in the luciferase signal and allergic phenotypes were measured in IL-4/Luc/CNS-1 transgenic (Tg) mice containing luciferase cDNA under control of the IL-4 promoter after exposure to 4% FA for 2 weeks. High levels of luciferase were detected in the abdominal region of the whole body and submandibular lymph node (SLN) of FA treated mice. Additionally, the ear thickness and IgE concentration were significantly upregulated in the FA treated group when compared with the acetone olive oil (AOO) treated group. FA treated mice showed enhanced auricular lymph node (ALN) weight, epidermis and dermis thickness, and infiltration of inflammatory cells. Furthermore, the expression of IL-6 among T helper 2 cytokines was higher in the FA treated group than the AOO treated group, while vascular endothelial growth factor (VEGF) levels remained constant. Overall, the results presented herein provide additional evidence that various allergic responses may be successfully induced in IL-4/Luc/CNS-1 Tg mice after exposure to low dose FA for 2 weeks. The luciferase signal under the IL-4 promoter may reflect general indicators of the allergic response induced by exposure to low dose FA.