Ｏ-033 Immunomodulatory Cell Induction for Tolerance after Pancreatic Islet Transplantation

◎Forgioni Agustina¹ 　渡辺 正明² 　後藤 了一¹ 　原田 拓弥¹ 　太田 拓児¹ 　嶋村 剛³ 　武冨 紹信¹
北海道大学大学院医学研究院消化器外科学教室Ⅰ¹ 北海道大学移植外科 ² 北海道大学病院臓器移植医療部 ³

Background: Pancreatic islet transplantation (PITx) is a promising treatment option for patients with type 1 diabetes mellitus. We have previously induced tolerance after liver transplantation by adoptive transfer of donor-antigen specific immunomodulatory cells (IMCs), where 70% of patients were successfully weaned off immunosuppressants. We hypothesize that the same beneficial effects could be applied to PITx.Methods: IMCs were induced by co-culturing C57BL/6 (H-2b) mouse splenocytes with irradiated BALB/c (H-2d) splenocytes in the presence of anti-CD80/86 monoclonal antibodies (mAbs,10 μg/mL). The changing of phenotypes during the 7-day culture was assessed by FACS analysis, and the immunosuppressive effects were evaluated by MLR.Results: After a 7-day co-culturing, the cell number decreased from 80x106 to 8.3±3.9x106 (mAbs group) and to 6.5±3.7x106 cells (w/o mAbs group) (mean±SD, n=4). The CD3+ T cells decreased from 25.4±21.2 % to 6.9±2.8 % (mAbs group), and to 7.4±3.4 % (w/o mAbs group), respectively. The CD4+ and CD8+ T cells increased in both groups: CD4+ T cells: 46.2±4.3 % to 60±11.5 % in the m Abs group and to 66.7±10 % in the w/o mAbs group; CD8+ T cells: 20.1±3.7 % to 33.9±16.7 % in the mAbs group and to 34.7±21.5 % in the w/o mAbs group. Regulatory T cells (CD4+CD25+FOXP3+) were significantly reduced in the mAbs group (2.7±1 % to 1.1±0.9 %, p = 0.019). However, IMCs suppressed the proliferation of C57BL/6 responder cells cultured with BALB/c stimulator cells in MLR. IMCs were also successfully injected into the liver together with islets in a mouse allogeneic PITx setting.Conclusion: IMCs showed immunosuppressive effects in vitro and could be safely injected in mouse PITx model. Further studies are required to thoroughly assess their anti-inflammatory and immunosuppressive effects and the beneficial effects in PITx.