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Biotech / Medical : Repligen Corp (RGEN) -- Ignore unavailable to you. Want to Upgrade?

To: scaram(o)uche who wrote (146)	9/27/1999 12:12:00 PM
From: scaram(o)uche	Read Replies (2) \| Respond to of 395

Blood 1999 Oct 1;94(7):2523-2529 Stable Mixed Hematopoietic Chimerism in Dogs Given Donor Antigen, CTLA4Ig, and 100 cGy Total Body Irradiation Before and Pharmacologic Immunosuppression After Marrow Transplant. Storb R, Yu C, Zaucha JM, Deeg HJ, Georges G, Kiem HP, Nash RA, McSweeney PA, Wagner JL Clinical Research Division, Fred Hutchinson Cancer Research Center; and the Department of Medicine, University of Washington, Seattle, WA. [Record supplied by publisher] Stable mixed chimerism can be established in dogs given a sublethal dose of 200 cGy total body irradiation (TBI) before and immunosuppression with mycophenolate mofetil (MMF) and cyclosporine (CSP) for 28 and 35 days, respectively, after dog leukocyte antigen-identical marrow transplantation. Most likely, the role of pretransplant TBI was to provide host immunosuppression, since stable mixed chimerism was also achieved in MMF/CSP-treated dogs when 450 cGy irradiation, targeted to cervical, thoracic, and upper abdominal lymph nodes, was substituted for TBI. When TBI was reduced from 200 to 100 cGy, all grafts were rejected within 3 to 12 weeks. Here, we asked whether stable engraftment after 100 cGy TBI could be accomplished by first reducing the intensity of host immune responsiveness with help of the fusion peptide CTLA4Ig, which blocks T-cell costimulation through the B7-CD28 signal pathway. Accordingly, recipient T cells were activated with intravenous (IV) injections of 10(6) donor peripheral blood mononuclear cells (PBMC)/kg per day on days -7 to -1 before 100 cGy TBI, with concurrent administration of CTLA4Ig 4 mg/kg/d IV. All 7 dogs so treated showed initial mixed chimerism. Two rejected their allografts after 8 and 20 weeks, respectively, and survived with autologous marrow recovery; 1 mixed chimera was unevaluable because of death at 3 weeks from intussusception; and 4 showed persisting mixed chimerism, including unirradiated marrow and lymph node spaces, for now more than 46 to 70 weeks after transplant. Data support the hypothesis that stable marrow allografts can be established by combining nonmyeloablative pretransplant host immunosuppression with posttransplant host and donor cell immunosuppression using MMF/CSP.