Contact hypersensitivity models in mice.

The contact hypersensitivity (CHS) reaction is commonly utilized to study cell-mediated host immune responses to epicutaneously applied allergens. This reaction is divided into two distinct phases, the afferent phase and the efferent phase. During the afferent phase of this model, mice are exposed to a contact allergen, which is typically a hapten that is applied to a location distal to the site of elicitation. Following a brief intermission, mice are reexposed to the contact allergen during the elicitation phase at a site proximal to the location of sensitization. In mice, the pinna of the ear is typically utilized to evaluate the elicitation phase. While the CHS reaction is typically utilized to study Th1-mediated immune responses, it is now evident that Th2 and Th17 cells also contribute during the elicitation phase of the model. Likewise, in humans, elevated immune responses to contact allergens are associated with a variety of atopic diseases. Here, we describe a common protocol for the induction and assessment of the CHS reaction in mice.