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Graft-versus-host disease (GVHD) is a major obstacle in allogeneic hematopoietic cell transplantation. Given the dynamic changes in immune cell subsets and tissue organization, which occur in GVHD, localization and timing of critical immunological events in vivo may reveal basic pathogenic mechanisms. To this end, we transplanted luciferase-labeled allogeneic splenocytes and monitored tissue distribution by in vivo bioluminescence imaging. High-resolution analyses showed initial proliferation of donor CD4 ؉ T cells followed by CD8 ؉ T cells in secondary lymphoid organs with subsequent homing to the intestines, liver, and skin. Transplantation of purified naive T cells caused GVHD that was initiated in secondary lymphoid organs followed by target organ manifestation in gut, liver, and skin. IntroductionAllogeneic hematopoietic cell transplantation (HCT) has proven to be an effective therapy for a variety of life-threatening malignancies. 1 The beneficial effects of HCT are due to the graft-versustumor reaction, which is capable of destroying residual tumor cells that persist after chemotherapy or radiation therapy. 2 However, allogeneic HCT is limited by the immunologic recognition and destruction of host tissues, termed graft-versus-host disease (GVHD). Acute GVHD continues to be a major source of morbidity and mortality following HCT, which limits treatment of a broader spectrum of diseases, such as autoimmune diseases or organ transplant rejection. 3,4 Tissue-specific destruction of GVHD target organs, as gastrointestinal tract, liver, and skin, underlines the importance of migration capacities of alloreactive T lymphocytes. 5,6 In the current study we aimed to determine the time points of organ infiltration and focused on the role of different lymphoid organs in initiating acute GVHD. We used in vivo bioluminescence imaging (BLI) to analyze the migration pattern of whole splenocytes after transplantation into allogeneic recipients. BLI has already proven to be a sensitive and accurate means of characterizing engraftment patterns of hematopoietic stem cells, of monitoring tumor cell growth, and of assessing response to conventional and biological therapies. [7][8][9] We also aimed to clarify the role of different T-cell subsets during GVHD development. It is reported in the literature [10][11][12] that CD4 ϩ effector memory T (T EM ) cells do not cause GVHD. This prompted us to characterize their trafficking and proliferation pattern in vivo, while comparing it to purified naive CD4 ϩ T lymphocytes. Materials and methods MiceFVB/N (H-2 q , Thy1.1) mice and Balb/c mice (H-2 d , Thy1.2) were purchased from Jackson Laboratory (Bar Harbor, ME). The luciferaseexpressing (luc ϩ ) transgenic FVB/N line was generated as previously described. 9 Female heterozygous luc ϩ offspring of the transgenic founder line FVB-L2G85 were used for all transplantation experiments. All animal studies were performed under institutional approval. Flow cytometric cell purification and analysisThe following antibodies were purchased from...

Program analysis and verification require decision procedures to reason on theories of data structures. Many problems can be reduced to the satisfiability of sets of ground literals in theory T . If a sound and complete inference system for first-order logic is guaranteed to terminate on T -satisfiability problems, any theorem-proving strategy with that system and a fair search plan is a T -satisfiability procedure. We prove termination of a rewrite-based first-order engine on the theories of records, integer offsets, integer offsets modulo and lists. We give a modularity theorem stating sufficient conditions for termination on a combinations of theories, given termination on each. The above theories, as well as others, satisfy these conditions. We introduce several sets of benchmarks on these theories and their combinations, including both parametric synthetic benchmarks to test scalability, and real-world problems to test performances on huge sets of literals. We compare the rewrite-based theorem prover E with the validity checkers CVC and CVC Lite. Contrary to the folklore that a general-purpose prover cannot compete with reasoners with built-in theories, the experiments are overall favorable to the theorem prover, showing that not only the rewriting approach is elegant and conceptually simple, but has important practical implications.

In acute graft-versus-host disease (aGVHD), donor T cells attack the recipient's gastrointestinal tract, liver, and skin. We hypothesized that blocking access to distinct lymphoid priming sites may alter the specific organ tropism and prevent aGVHD development. In support of this initial hypothesis, we found that different secondary lymphoid organs (