Vaccination with <i>S</i>. Typhimurium TAS2010 induces enhanced memory formation in CD4⁺ T cells.

Wild-type C57BL/6 mice were either naïve or i.v. injected with 200cfu TAS2010 or BRD509. A-D) At week 10 post-vaccination, A) the total number of CD4+ T cells in the spleen, and B) the frequency of CD4+ T cells expressing indicated activation/memory markers are shown. C) Representative FACS plots and D) summarised data of the percentage of CD4+ T cells producing IFN-γ following ex vivo re-stimulation with 5×107cfu heat-killed S. Typhimurium SL1344 (HKSTm), with unstimulated (unstim) cells set up as the control. Data from individual mice are shown as symbols with group mean, pooled from 3 independent experiments. Unpaired t-tests were used for statistical analysis between the two vaccination groups. E-G) Conventional CD4+ T cells were analysed at week 15 post-vaccination, with NKT cells excluded using a CD1d α-galactosylceramide (α-GalCer) tetramer. E) Representative FACS plots of conventional CD4+ T cells in the liver of naïve or vaccinated mice to show the frequency of CD44hiCD69+ CD4+ T cells; these cells (black line) also express high level of CXCR3 and CXCR6 compared to the unstained control (grey shade). F) The number of CD44hiCD69+ CD4+ T cells is calculated per liver. G) The frequency of liver-bound CD4+ T cells producing IFN-γ in response to ex vivo re-stimulation was determined. Data from individual mice are shown as symbols with group mean, pooled from 3 independent experiments. Unpaired t-tests were used for statistical analysis between the two vaccination groups.