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
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.
