Transplantation of transgenic luciferase+ splenocytes. (A) Transplantation of allogeneic FVB/N splenocytes induces acute lethal GVHD in a cell dose dependent manner. All animals that received transplants of 5 × 106 allogeneic bone marrow cells (□; n = 10) survive without GVHD, whereas mice receiving lethal irradiation (800 rad) without subsequent HCT die of the consequences of myeloablation (×; n = 7). HCT recipients that received transplants of 5 × 106 allogeneic bone marrow plus 5 × 105 allogeneic splenocytes (▴; n = 10), or plus 1 × 106 allogeneic splenocytes (▾; n = 10) develop acute GVHD. Mice that received transplants of bone marrow plus 4 × 106 allogeneic splenocytes die of lethal acute GVHD within 2 weeks after HCT (♦;n = 10). Displayed are pooled results from 2 independent experiments. (B) BLI and (C) ex vivo imaging demonstrate a dynamic process of cell proliferation and migration with distinct distribution patterns in syngeneic versus allogeneic HCT recipients. Syngeneic splenocytes (top row) home initially predominantly to the liver and display signs of hematopoietic engraftment by day 6. By day 14, syngeneic HCT display predominant signals from the bone such as femura, pelvis, and sternum, but also spleen and thymus. Allogeneic transplanted splenocytes (bottom panel) initially proliferate in secondary lymphoid organs before infiltrating the intestines at day 4, liver and skin (ears) between day 5 and 6. Animals with an oversaturating light signal are displayed with increased signal thresholds to resolve the predominant organ distribution. One representative animal for each group is shown over time. Ex vivo imaging of the gastrointestinal tract and spleen of syngeneic animals (C, top row) reveals only transient migration of splenocytes to Peyer patches and mesenteric lymph nodes but an increase of light emission from the spleen. In contrast, allogeneic splenocytes (C, bottom row) migrate to and proliferate in these lymphoid organs before infiltrating mucosal sites. Signals from the entire intestines start to peak at day 6 before animals succumb to acute lethal GVHD.
