Small intestine intraepithelial CD4+ T cells after Toxoplasma gondii infection. Mus musculus

Retention of lymphocytes in the intestinal mucosa requires specialized chemokine receptors and adhesion molecules. Here we find that both CD4+CD8+ and CD4+T cells in the intestinal epithelium, as well as CD8+T cells in the intestinal mucosa and mesenteric lymph nodes, express the cell adhesion molecule Crtam upon activation, whereas the ligand of Crtam, Cadm1, is expressed on gut CD103+DCs. Lack of Crtam-Cadm1 interactions in Crtam-/- and Cadm1-/- mice results in loss of CD4+CD8+T cells, which arise from mucosal CD4+T cells that acquire a CD8 lineage expression profile. Following acute oral infection with T. gondii, both WT and Crtam-/- mice mounted a robust TH1 response, but markedly fewer TH17 cells were present in the intestinal mucosa of Crtam-/- mice. The almost exclusive TH1 response in Crtam-/- mice resulted in more efficient control of intestinal T. gondii infection. Overall design: CD4+ T cells were cell sorted to analyze the differences resulting from the lack of Crtam expression during T. gondii infection.