T Helper Cell Type 1–associated and Cytotoxic T Lymphocyte–mediated Tumor Immunity Is Impaired in Interleukin 4–deficient Mice

It is widely accepted that cellular immune responses are induced by CD4+ T helper 1 (Th1) cells secreting interleukin (IL)-2 and interferon (IFN)-γ. Tumor immunity is often mediated by cytotoxic T lymphocytes (CTLs) whose activation is supported by Th1 cytokines. Since IL-4 directs Th2 development and has been shown to inhibit Th1-dominated responses, we assumed that IL-4–deficient (IL-4−/−) mice would develop vigorous CTL-mediated tumor immunity compared with IL-4–competent (IL-4+/+) mice. Surprisingly, IL-4−/− mice were severely impaired to develop tumor immunity to both a mammary adenocarcinoma line and a colon carcinoma line. The lack of tumor immunity in IL-4−/− mice was associated with reduced IFN-γ production, diminished levels of tumor-reactive serum IgG2a, and undetectable CTL activity, indicating a defective Th1 response in the absence of endogenous IL-4. Anti–IL-4 monoclonal antibody blocked tumor immunity in IL-4+/+ mice when administered at the time of immunization but not at the time of challenge. Additionally, tumor immunity could be induced in IL-4−/− mice, if IL-4 was provided by gene-modified cells together with immunizing tumor cells. These results demonstrate that tumor immunity requires IL-4 in the priming phase for the generation of effector cells rather than for their maintenance and exclude secondary, developmental defects in the “knockout” strain. Together, our results demonstrate a novel and previously unanticipated role of IL-4 for the generation of Th1-associated, CTL-mediated tumor immunity

Generation of Tumor-associated Cytotoxic T Lymphocytes Requires Interleukin 4 from CD8+ T Cells

Activation of tumor-associated CD8+ cytotoxic T lymphocytes (CTLs) often requires antigen representation, e.g., by dendritic cells (DCs), and CD4+ T cell help. Previously, we showed that CTL-mediated tumor immunity required interleukin 4 (IL-4) during the immunization but not effector phase. To determine the source and target cells of IL-4, we performed adoptive T cell transfers using CD4+ and CD8+ T cells from IL-4−/− and IL-4R−/− mice and analyzed CTL generation. Even though necessary for CTL generation, CD4+ T cells did not need to express IL-4 or IL-4R. Surprisingly, CTL generation required IL-4 but not IL-4R expression by CD8+ T cells. As IL-4 (a) was expressed by naive CD8+ T cells within 24 h after antigen encounter, (b) IL-4 induced DC maturation, and (c) CTL development was impaired in T cell–reconstituted IL-4R−/− mice, CD8+ T cell–derived IL-4 appears to act on DCs. We conclude that CD4+ and CD8+ T cells provide different signals for DC activation during CTL generation

Adoptive transfer of IL-4Rα+ macrophages is sufficient to enhance eosinophilic inflammation in a mouse model of allergic lung inflammation

<p>Abstract</p> <p>Background</p> <p>The IL-4 receptor α (IL-4Rα) chain has a broad expression pattern and participates in IL-4 and IL-13 signaling, allowing it to influence several pathological components of allergic lung inflammation. We previously reported that IL-4Rα expression on both bone marrow-derived and non-bone marrow-derived cells contributed to the severity of allergic lung inflammation. There was a correlation between the number of macrophages expressing the IL-4Rα, CD11b, and IA^d, and the degree of eosinophilia in ovalbumin challenged mice. The engagement of the IL-4Rα by IL-4 or IL-13 is able to stimulate the alternative activation of macrophages (AAM). The presence of AAM has been correlated with inflammatory responses to parasites and allergens. Therefore, we hypothesized that IL-4Rα⁺AAM play an active role in allergic lung inflammation. To directly determine the role of AAM in allergic lung inflammation, M-CSF-dependent macrophages (BMM) were prepared from the bone-marrow of IL-4Rα positive and negative mice and transferred to IL-4RαxRAG2^-/-mice. Wild type TH2 cells were provided exogenously.</p> <p>Results</p> <p>Mice receiving IL-4Rα^+/+BMM showed a marked increase in the recruitment of eosinophils to the lung after challenge with ovalbumin as compared to mice receiving IL-4Rα^-/-BMM. As expected, the eosinophilic inflammation was dependent on the presence of TH2 cells. Furthermore, we observed an increase in cells expressing F4/80 and Mac3, and the AAM marker YM1/2 in the lungs of mice receiving IL-4Rα^+/+BMM. The BAL fluid from these mice contained elevated levels of eotaxin-1, RANTES, and CCL2.</p> <p>Conclusions</p> <p>These results demonstrate that transfer of IL-4Rα + macrophages is <it>sufficient </it>to enhance TH2-driven, allergic inflammation. They further show that stimulation of macrophages through IL-4Rα leads to their alternative activation and <it>positive contribution </it>to the TH2-driven allergic inflammatory response in the lung. Since an increase in AAM and their products has been observed in patients with asthma exacerbations, these results suggest that AAM may be targeted to alleviate exacerbations.</p

Transforming Growth Factor-β Production and Myeloid Cells Are an Effector Mechanism through Which CD1d-restricted T Cells Block Cytotoxic T Lymphocyte–mediated Tumor Immunosurveillance: Abrogation Prevents Tumor Recurrence

Our previous work demonstrated that cytotoxic T lymphocyte (CTL)-mediated tumor immunosurveillance of the 15-12RM tumor could be suppressed by a CD1d-restricted lymphocyte, most likely a natural killer (NK) T cell, which produces interleukin (IL)-13. Here we present evidence for the effector elements in this suppressive pathway. T cell–reconstituted recombination activating gene (RAG)2 knockout (KO) and RAG2/IL-4 receptor α double KO mice showed that inhibition of immunosurveillance requires IL-13 responsiveness by a non–T non–B cell. Such nonlymphoid splenocytes from tumor-bearing mice produced more transforming growth factor (TGF)-β, a potent inhibitor of CTL, ex vivo than such cells from naive mice, and this TGF-β production was dependent on the presence in vivo of both IL-13 and CD1d-restricted T cells. Ex vivo TGF-β production was also abrogated by depleting either CD11b+ or Gr-1+ cells from the nonlymphoid cells of tumor-bearing mice. Further, blocking TGF-β or depleting Gr-1+ cells in vivo prevented the tumor recurrence, implying that TGF-β made by a CD11b+ Gr-1+ myeloid cell, in an IL-13 and CD1d-restricted T cell–dependent mechanism, is necessary for down-regulation of tumor immunosurveillance. Identification of this stepwise regulation of immunosurveillance, involving CD1-restricted T cells, IL-13, myeloid cells, and TGF-β, explains previous observations on myeloid suppressor cells or TGF-β and provides insights for targeted approaches for cancer immunotherapy, including synergistic blockade of TGF-β and IL-13