Mice with homologous disruption of the interferon γ(IFN-γ) gene on the C57BL/6 background were infected witly Leishmania major and the immune response assessed. In contrast to wild-type or heterozygous knockout mice...Mice with homologous disruption of the interferon γ(IFN-γ) gene on the C57BL/6 background were infected witly Leishmania major and the immune response assessed. In contrast to wild-type or heterozygous knockout mice,deficient animals were unable to restrict growth of the parasite and suffered lethal infection over 6￣8 wk.Although wild-type and heterozygous littermates developed CD4+ cells that contained transcripts for IFN-γ and lymphotoxin,tipical of T helper type 1(Th1) cells, the knockout mice developed CD+4 cells that contained transcripts for interleukin 4(IL-4),IL-5,and IL13,typical of Th2 cells. ELISPOT assays confirmed the reciprocal patterns of IFN-γ or IL-4 production by T cells in similar frequencies in the respective groups of mice,and antibody analysis confirmed the presence of Th2-mediated isotype switching in the knockout mice. These data suggest that CD4+ T cells that normally respond to antigens by differentiation to Th1 cells default to the Th2 pathway in the absence of endogenous IFN-γ.展开更多
Low-dose total body irradiation （LTBI） is used in the treatment of some cancers mainly for immune enhancement rather than cell killing. However, the mechanism underlying LTBI remains unknown. In this study, by analy...Low-dose total body irradiation （LTBI） is used in the treatment of some cancers mainly for immune enhancement rather than cell killing. However, the mechanism underlying LTBI remains unknown. In this study, by analyzing the immune patterns of lymphocytes, we found that the percentage and absolute number of CD4^＋CD25^＋Foxp3^＋ regulatory T cells are markedly decreased in naive mice following treatment with LTBI. On the contrary, the CD4^＋CD44^＋/CD8^＋CD44^＋ effector-memory T cells are greatly increased. Importantly, naive mice treated with dendritic cell-gp100 tumor vaccines under LTBI induced an enhancement of antigen-specific proliferation and cytotoxicity as well as interferon-γ, （IFN-γ） secretion against FIO melanoma tumor challenge, compared to treatment with either the tumor vaccine or LTBI alone. Consequently, the treatment resulted in a reduced tumor burden and prolonged mouse survival. Our data demonstrate that LTBI＇s enhancement of antitumor immunity was mainly associated with selectively decreasing the proportion and number of T regulatory cells, implying the potential application of the combination of LTBI and a tumor vaccine in antitumor therapy.展开更多
文摘Mice with homologous disruption of the interferon γ(IFN-γ) gene on the C57BL/6 background were infected witly Leishmania major and the immune response assessed. In contrast to wild-type or heterozygous knockout mice,deficient animals were unable to restrict growth of the parasite and suffered lethal infection over 6￣8 wk.Although wild-type and heterozygous littermates developed CD4+ cells that contained transcripts for IFN-γ and lymphotoxin,tipical of T helper type 1(Th1) cells, the knockout mice developed CD+4 cells that contained transcripts for interleukin 4(IL-4),IL-5,and IL13,typical of Th2 cells. ELISPOT assays confirmed the reciprocal patterns of IFN-γ or IL-4 production by T cells in similar frequencies in the respective groups of mice,and antibody analysis confirmed the presence of Th2-mediated isotype switching in the knockout mice. These data suggest that CD4+ T cells that normally respond to antigens by differentiation to Th1 cells default to the Th2 pathway in the absence of endogenous IFN-γ.
文摘Low-dose total body irradiation （LTBI） is used in the treatment of some cancers mainly for immune enhancement rather than cell killing. However, the mechanism underlying LTBI remains unknown. In this study, by analyzing the immune patterns of lymphocytes, we found that the percentage and absolute number of CD4^＋CD25^＋Foxp3^＋ regulatory T cells are markedly decreased in naive mice following treatment with LTBI. On the contrary, the CD4^＋CD44^＋/CD8^＋CD44^＋ effector-memory T cells are greatly increased. Importantly, naive mice treated with dendritic cell-gp100 tumor vaccines under LTBI induced an enhancement of antigen-specific proliferation and cytotoxicity as well as interferon-γ, （IFN-γ） secretion against FIO melanoma tumor challenge, compared to treatment with either the tumor vaccine or LTBI alone. Consequently, the treatment resulted in a reduced tumor burden and prolonged mouse survival. Our data demonstrate that LTBI＇s enhancement of antitumor immunity was mainly associated with selectively decreasing the proportion and number of T regulatory cells, implying the potential application of the combination of LTBI and a tumor vaccine in antitumor therapy.
