IL4 and infection: Furthermore, we observed that egg retention induces the activation of a Th2 response even in the absence of the ST2 receptor, as seen by the concentrations of IL-4 and IL-13 in the liver; however, this response is not maintained in the chronic phase of infection, when ST2−/− mice showed significantly lower levels of these cytokines than the infected WT mice (Figure 2C,D).