Tumor immunity: a balancing act between T cell activation, macrophage activation and tumor-induced immune suppression
The mouse 4T1 mammary carcinoma is a BALB/c-derived tumor that spontaneously metastasizes and induces immune suppression. Although >95% of wild type BALB/c mice die from metastatic 4T1 tumor even if the primary mammary tumor is surgically removed, >65% of BALB/c mice with a deleted Signal Transducer Activator of Transcription 6 (STAT6) gene survive post-surgery. STAT6-deficiency also confers enhanced immunity against spontaneously developing breast cancer since NeuT+/− mice that are STAT6-deficient develop mammary tumors later and survive longer than NeuT+/− mice that are STAT6-competent. Rejection of metastastic disease and survival of STAT6-deficient mice after removal of primary tumor involve three mechanisms: (1) The generation of M1 type macrophages that produce nitric oxide and are tumoricidal; (2) A decrease to normal in the elevated levels of myeloid suppressor cells that accumulate during primary tumor growth; and (3) CD8+ tumor-specific T lymphocytes. STAT6-deficient, but not wild type BALB/c, mice generate nitric oxide producing macrophages because they lack the STAT6 transcription factor which is necessary for signaling through the type 2 IL-4Rα complex, and which induces the production of arginase instead of nitric oxide.
KeywordsTumor-induced immune suppression Immune surveillance M1 macrophages Metastatic breast cancer Cell-mediated tumor immunity
- 3.Boggio K, Nicoletti G, Di Carlo E, Cavallo F, Landuzzi L, Melani C, Giovarelli M, Rossi I, Nanni P, De Giovanni C, Bouchard P, Wolf S, Modesti A, Musiani P, Lollini PL, Colombo MP, Forni G (1998) Interleukin 12-mediated prevention of spontaneous mammary adenocarcinomas in two lines of Her-2/neu transgenic mice. J Exp Med 188:589CrossRefPubMedGoogle Scholar
- 25.Pulaski BA, Clements VK, Pipeling MR, Ostrand-Rosenberg S (2000a) Immunotherapy with vaccines combining MHC class II/CD80+ tumor cells with interleukin-12 reduces established metastatic disease and stimulates immune effectors and monokine induced by interferon gamma. Cancer Immunol Immunother 49:34CrossRefPubMedGoogle Scholar
- 26.Pulaski BA, Terman DS, Khan S, Muller E, Ostrand-Rosenberg S (2000b) Cooperativity of Staphylococcal aureus enterotoxin B superantigen, major histocompatibility complex class II, and CD80 for immunotherapy of advanced spontaneous metastases in a clinically relevant postoperative mouse breast cancer model. Cancer Res 60:2710PubMedGoogle Scholar
- 31.Sinha P, Clements VK, Ostrand-Rosenberg S (2005) Reduction of myeloid-derived suppressor cells and induction of m1 macrophages facilitate the rejection of established metastatic disease. J Immunol 174:636Google Scholar