1E). Comparison of other lymphocyte subsets between IL-10 KO and RG7204 mouse IL-10/IL-4 KO mice revealed only a slight and variable decrease in CD8+ T cell numbers in IL-10 KO animals (data not shown). Overall, the data supported the contention that IL-10 prevented hepatocyte

injury and accumulation of intestinally-derived CD4+ cells, whereas IL-4 was required for the development of hepatic necrosis. To investigate further the role of IL-4 in the liver during infection, we sought to determine which cell type(s) produced it. The majority of IL-4+ cells were CD4+; however, the percentage of CD4+IL-4+ cells in IL-10 KO mice was approximately twice that in WT mice (Fig. 2A). Most CD4+ cells in the liver are conventional CD4+ T cells, but some classical natural killer (NK) T cells also express CD4. To distinguish between contributions from these two cell

types, we stained cells for CD4, IL-4, and NK1.1. IL-4+ cells were gated, and the percentages of IL-4 expressing conventional CD4+ T cells versus NK T cells are shown in Fig. 2B. Almost all of the IL-4+ cells colocalized with Abiraterone the CD4+NK1.1− population. Thus, CD4+ T cells were the major source of IL-4. Additionally, this population was expanded in IL-10 KO animals in comparison with WT mice. Because we previously discovered that an intestinal immune response was a prerequisite for hepatic (-)-p-Bromotetramisole Oxalate inflammation, we asked if any CD4+NK1.1−IL-4+ cells were gut-derived. CCR9, like α4β7, is up-regulated on lymphocytes after activation within gut-associated lymphoid tissue (GALT) and is used as a marker of intestinal origin. 15 Infected IL-10 KO animals had significantly more IL-4+, intestinally

derived CD4+ T cells than WT mice (Fig. 2C). Previously, we noted that lesions in infected IL-10 KO mice contained an abundance of granulocytes, including neutrophils and eosinophils. IL-4 promotes eosinophil proliferation, recruitment, and effector functions, and its expression is elevated by T. spiralis infection. 16 This led us to ask if eosinophils were involved in the development of hepatic necrosis. We compared eosinophil infiltration in singly and doubly deficient mice after infection (Fig. 3A). As expected, IL-4 KO mice displayed reduced eosinophilia in comparison with WT animals. In contrast, eosinophil numbers were higher in infected IL-10 KO mice compared to WT animals. The hepatic eosinophil content in IL-10/IL-4 KO mice was similar to that in WT mice. Hence, eosinophil accumulation in the liver was inhibited by IL-10 and promoted by IL-4. We tested whether eosinophils were essential in the development of hepatic necrosis by mating IL-10 KO animals to eosinophil-deficient (PHIL) mice to generate mice lacking both IL-10 and eosinophils.