1. MP cells, but not pathogen-elicited effector CD4+ T lymphocytes, rapidly produce IFN-γ during T. gondii infection independently of pathogen antigens.
MP cells, but not pathogen-elicited effector CD4+ T lymphocytes, rapidly produce IFN-γ during T. gondii infection independently of pathogen antigens. (A to C) MP cells rapidly produce IFN-γ during T. gondii infection in the absence of pathogen recognition. (A) IFN-γ–eYFP reporter mice treated with anti–I-Aβ mAb or control IgG were infected with T. gondii, and CD44hi CD62Llo CD25lo CD4+ T cells from the PC and spleen were analyzed at the indicated days. The numbers in the representative histograms indicate the frequency of IFN-γ–eYFP+ cells among each group. The graphs show the number (mean ± SD) of IFN-γ–YFP+ cells from each group (n = 2 to 3). Data are representative of two independent experiments. (B) T. gondii–infected IFN-γ–eYFP reporter mice were treated with or without CsA, and splenic CD44hi CD62Llo CD25lo CD4+ T cells were analyzed for IFN-γ–eYFP expression on days 2 and 7. The graph shows the number (mean ± SD) of IFN-γ+ cells (n = 2 to 3). (C) IFN-γ mRNA expression in sorted eYFPhi and eYFPlo MP cells obtained from PC and spleen was measured by qPCR. The graph shows its expression (mean ± SD) relative to β-actin (n = 3). (D to F) Existing MP cells are the major source of IFN-γ on day 2 after T. gondii infection. (D) Experimental design. CD45.1/1 Rag KO mice, which received, first, 1 × 106 total CD4+ T cells from CD45.1/2 IFN-γ–eYFP reporter mice (day −28) and, 3 weeks later, 107 naïve CD4+ T cells from CD45.2/2 IFN-γ–eYFP reporter mice (day −7), were infected with T. gondii (day 0), and CD45.2+ donor cells including both CD45.1/2 and CD45.2/2 populations were analyzed on days 0, 2, and 7. iv, intravenous injection. (E) The histogram shows IFN-γ–eYFP expression by naïve and MP CD45.2+ CD4+ T cells, whereas the numbers in the representative dot plots show the frequency of CD45.1/2 and CD45.2/2 cells among naïve and MP CD45.2+ CD4+ T lymphocytes on day 0 (n = 6). (F) IFN-γ–eYFP expression by naïve and MP CD45.2+ CD4+ T cells is shown in the histograms, whereas the dot plots show the frequency of CD45.1/2 and CD45.2/2 donor cell populations among IFN-γ+ CD44hi CD62Llo CD25lo CD45.2+ CD4+ T cells in the spleen on days 2 and 7. The graph shows the frequency (mean ± SD) of CD45.1/2 and CD45.2/2 donor cells among each group (n = 4). Data are pooled from four independent experiments. *P < 0.05, **P < 0.01, ***P <
Takeshi Kawabe et al. Sci. Immunol. 2017;2:eaam9304
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