Using Cytokine Reporter Mice to Visualize Type-2 Immunity In Vivo.

Type-2 cytokine production plays a critical role in the context of type 2 immunity and allergic inflammation. Interleukin-4 (IL-4) and IL-13 are key modulators of the cell-mediated and humoral immune hallmarks most commonly associated with type-2 immune responses. However, production of these cytokines by lymphocytes and their tissue localization has been difficult to detect in vivo. As such, the field has relied heavily on ex vivo restimulation and in vitro differentiation assays to understand type-2 cytokine biology. Although these studies have greatly informed our understanding of type-2 cytokine regulation, it is becoming increasingly clear that the data does not always provide a true accounting of the complexity of type-2 immune cell biology in vivo. Described below is a protocol used to detect IL-4-competent and protein-producing cells in the lung and lymph nodes of mice after infection with a helminth. Importantly, this protocol has also been used to successfully identify reporter expression and cell function in vivo using various other cytokine-reporter systems.