Figure 2

Ischemia increases the brain concentration of S1P and the recruitment of S1P⁺ T cells. (a,b) S1P concentration was measured by mass spectrometry in the contralateral and ipsilateral (ischemic) brain hemispheres 24 h after MCAo (n = 10 mice). Illustrative ionograms of representative samples of each brain hemisphere and the corresponding internal standard (IS) are shown in (a). Cps indicates counts per second. Ischemia significantly increased S1P concentration in the ipsilateral hemisphere (Mann-Whitney test, **p = 0.007) (b). (c) The presence of S1P1⁺ T cells in the ipsilateral and contralateral brain hemispheres was evaluated 4 days post-ischemia by flow cytometry (n = 7). Ischemia significantly increased S1P1⁺ CD3⁺ T cell number (Mann-Whitney test, *p = 0.047). (d) Illustrative flow cytometry plots of contralateral and ipsilateral brain hemispheres show S1P1⁺ T cells in the ischemic tissue.