Accumulation of WT versus CCR7^−/− T_n cells within B6D2 recipients. B6D2 recipients were lethally irradiated and then administered 3 × 10⁶ TCD BM cells from WT B6 donors with or without 4 × 10⁶ CD25-depleted eGFP⁺ T_n cells from either WT B6 or CCR7^−/− B6 donors on day 0. (A-F) Recipient mice were anesthetized on transplantation day +15, and donor T-cell trafficking was studied using stereofluorescence microscopy. Tissues from 1 of 3 representative WT T_n cell recipients are depicted in the top panels, and tissues from 1 of 3 representative CCR7^−/− T_n cell recipients are depicted in the bottom panels. Images on the left of each panel depict actual eGFP fluorescence, while those on the right indicate the intensity of the eGFP signal (white > red > yellow > green > blue > black). (G-I) Recipient mice were anesthetized on transplantation day +3, and donor T-cell trafficking to SLTs was evaluated using stereofluorescence microscopy. Images are taken from 1 of 3 representative WT T_n cell recipients and from 1 of 3 CCR7^−/− T_n recipients. (J) Recipient animals were euthanized on transplantation day +15, and their organs were homogenized in a PBS/protease-inhibitor solution. After appropriate dilutions, eGFP levels were measured in each site using an anti-GFP ELISA kit. n = 4 per group. *P = .044; **P = .011; ***P = .002. Organs were pooled from a B6D2 mouse that received a transplant of TCD BM cells plus non–eGFP-expressing B6 T_n cells for control purposes. (K) Recipient animals were killed on transplantation day 3, and their spleens were homogenized for analysis by anti-GFP ELISA. n = 3 per group. *P = .002. Error bars for panels J and K indicate SEM.