T cells enter the brain after adoptive transfer into <i>R</i>. <i>typhi</i>-infected C57BL/6 RAG1^-/- mice.

<p>CD4⁺ and CD8⁺ T cells were purified from C57BL/6 mice 21 days post infection to obtain immune T cells. T cells were adoptively transferred into C57BL/6 RAG1^-/- on day 63 post infection with <i>R</i>. <i>typhi</i>, which is approximately 20 days prior to the onset of disease. Control mice received PBS instead of T cells (<b>A</b>). Blood cells were analyzed for the presence of CD4⁺ and CD8⁺ T cells by flow cytometry on day 7 post T cell transfer by flow cytometry. Dot plots show representative stainings of the blood from a control mouse, a CD4⁺ and a CD8⁺ T cell recipient. Graphs show the percentage (y-axis) of CD4⁺ and CD8⁺ T cells as indicated on the x-axis among blood leukocytes in the groups of CD4⁺ and CD8⁺ recipient mice (<b>B</b>). Brain cells were analyzed for the presence of CD4⁺ and CD8⁺ T cells by flow cytometry gated on CD45^high cells. Representative stainings of a naïve C57BL/6 mouse that was used as an additional control, a <i>R</i>. <i>typhi</i>-infected C57BL/6 RAG1^-/- control mouse and a CD4⁺ and CD8⁺ T cell recipient are shown. Graphs show the percentage (y-axis) of CD4⁺ and CD8⁺ T cells as indicated on the x-axis among CD45^high cells in the brains of the groups of CD4⁺ and CD8⁺ recipient mice (<b>C</b>). Each symbol represents a single mouse.