Donor T cell/DC interactions within recipient spleens on transplantation day +4. B6D2 recipients were lethally irradiated and administered 3 × 10⁶ TCD BM cells from WT B6 donors with 4 × 10⁶ CD25-depleted eGFP⁺ T_n cells from either WT B6 or CCR7^−/− B6 donors on day 0. Recipients were killed on transplantation day +4, and their spleens removed for immunofluorescence microscopy. Images are taken from 1 of 3 representative WT T_n cell recipients and from 1 of 3 CCR7^−/− T_n cell recipients. Donor cells are identified by their eGFP positivity (green). An anti-CD11c primary/Cy3-conjugated secondary antibody combination was used to visualize CD11c-expressing cells, which are predominantly DCs (red). (A,C) Recipients of WT T_n cells. (B,D) Recipients of CCR7^−/− cells. Original magnifications, ×4 (A-B) and ×10 (C-D).