Fig. 1

A subpopulation of effector CD8⁺ T cells expresses the c-Met receptor in EAE. MOG_35–55 gating strategy for the identification of c-Met-expressing CD8⁺ T cells. To characterize the frequency of CD8⁺ T cells that express c-Met, live lymphocyte gated in forward (FS Lin) versus side scatter (SS Lin) dot plots were selected, followed by a subsequent gate on live (7AAD^-) cells (not shown). CD8⁺ T lymphocytes were subsequently gated (CD45⁺CD3⁺CD8⁺ T cells). Numbers in the quadrants of the density plots (CD8 vs. c-Met) at acute phase (d14) indicate the percentage of the population CD8⁺c-Met⁺. Frequency values reflect results above the fluorescence values obtained by isotype control antibodies (a). Splenocytes, lymph node cells, or CNS mononuclear cells from MOG_35–55-immunized mice were harvested and stained with CD8-APC and c-Met-FITC and analyzed by flow cytometry. Data are gated on live CD8⁺ T cells. The frequency of c-Met⁺CD8⁺ cells in each organ is depicted (b top panel), as is the absolute number of c-Met⁺CD8⁺ cells (b lower panel), based on the counts of the total number of cells obtained. Results are the averages of at least n = 5 mice per group per time point (representative of 3 independent experiments). c CD8⁺ T cells from CNS were examined by flow cytometry for expression of the activation markers CD44 and CD62L (CD44^lowCD62L^high naive CD8⁺ T cells; CD44^highCD62L^low activated memory CD8⁺ T cells). Bars represent the mean ± standard error of values for n = 5 mice/group; *p ≤ 0.05, **p ≤ 0.01, and ***p ≤ 0.001 by Student’s t test. d Representative double immunofluorescent staining images for CD8 (red) and c-Met (green) of cytospin of spleen cells at peak disease. Cell nuclei were counterstained with DAPI (blue). Scale bar, 20 μm. Insets are magnified × 4.5 from the original images. The arrows indicate the area where we observed co-expression of both c-Met and CD8 markers. Comparable results were obtained with three other mice