Inhibitotory Effect of Cathepsin B Inhibitor CA 074 on Xenograft Rejection

Research Project

Project/Area Number	12671161
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	General surgery
Research Institution	Ehime University
Principal Investigator	KIYOCHI Hidenori Ehime University Hospital, Instructor, 医学部附属病院, 助手 (00314956)
Co-Investigator(Kenkyū-buntansha)	KOBAYASHI Nobuaki Ehime University, Faculty of Medicine, Professor, 医学部, 教授 (60135564)
Project Period (FY)	2000 – 2001
Project Status	Completed (Fiscal Year 2001)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,900,000) Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 2000: ¥3,200,000 (Direct Cost: ¥3,200,000)
Keywords	cathepsin B inhibitor / xenotransplantation / indirect recognition / CA074 / mixed lymphocyte reaction / antigen processin / 間接抗原認識 / 移植 / 異種 / プロテアーゼ / リンパ球培養 / カテプシン / 抗原提示 / マウス
Research Abstract	Due to species disparities, direct cellular interaction between donor antigen-presenting cells (APC) and recipient T lymphocytes is not strong in xenotransplantation. Indirect recognition, in which recipient T cells recognized processed donor antigens on the MHC class II cell surface molecules of recipient self APC, appears more significant than direct recognition in xenoantigen recognition. Cathepsin B is one of the determinant protease responsible for foreign antigen processing by APC. CA074 reported to be a potent specific inhibitor of cathepsin B. In the present study, immunosuppressive effect of cathepsin B inhibitor CA074 on indirect xeno-antigen recognition was investigated. One way mixed lymphocyte reaction (MLR) was performed in rat-to-mouse combination. B cell depleted B6 mouse splenocytes (2 x 10^5), including T cell and APC population, were used as responder. Irradiated (3000 rad) F344 rat erythrocytes (40 x 10^5) and splenocytes (4 x 10^5) were used for 'indirect' (Ind-MLR) and 'direct plus indirect' (Both-MLR) stimulation, respectively. CA074 100 mg/ml concentration suppressed xenogenic erythrocyte stimulated MLR (Ind-MLR), which is evoked by exclusively indirect recognition, to the control level. Xenogenic splenocyte stimulated MLR (Both-MLR), which include direct and indirect recognition was partially suppressed by CA074. By adding various concentrations, from 10 to 100 mg/ml, of CA074 to the culture, a dose-dependent inhibition was observed in Ind-MLR, and mitogenic responses by ConA were not affected by CA074. In conclusion, CA074 suppressed indirect xeno-antigen recognition on rat-to-mouse MLR by blocking the donor antigen processing in recipient APC. It will be a novel strategy for immunosuppression of xeno cellular response.