New method for controlling the rejection which are due to the expression suppression of the MHC class II molecule

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13671388
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thoracic surgery
• Research Institution: Dokkyo University School of Medicine
• Principal Investigator: MIYOSHI Shinichirou Cardiothoratic surgery, Professor, 医学部, 教授 (00190827)
• Co-Investigator(Kenkyū-buntansha): MINAMI Masato Osaka University, Assistant, 医学系研究科, 助手 (10240847) ; SUGUTA Kazuhiko Cardiothoratic surgery, Assistant, 医学部, 助手 (40216312) ; IKEDA Yasunori Cardiothoratic surgery, Instructor, 医学部, 講師 (80202901) ; OKUMURA Meinoshin Osaka University, Assistant, 医学系研究科, 助手 (40252647)
• Project Period (FY): 2001 – 2002
• Keywords: organ transplantation / transplantation immunity / rejection

Research Abstract

Control of rejection of the graft and evading infection are the essential subjects for successful organ transplantation. Although effective immunosuppressants, including cyclosporine and tacrolimus, have contributed to improvement of the organ transplantation, additional methods for suppression of graft rejection are still required.
The immunological target in organ transplantation is known to be major histocompatability complex (MHC), and in human, especially HLA-DR molecule is supposed to be the most important antigen. In the present study, we tried to develop a new gene therapy method to down-regulate the expression of HLA-DR molecule in the transplanted organs by interfering the function of MHC class II transactivator (CIITA) molecule, a key transcription factor of MHC class II molecules.
CIIA molecule consists of two portions, an amino-terminus site which is essential in activating the promoter of HMC II genes and a carboxylterminus site which binds to other DNA binding proteins. A deletion mutant protein which expresses only the binding domain is supposed to work as a dominant negative mutation and to suppress the expression of MHC II molecules. The DNA product whose sequence corresponds to the binding domain of the CIITA molecule was derived by the method of RT-PCR. The derived DNA product was inserted into the expression vector, and the DNA construct of dominant negative mutation of CIITA was created.
The DNA construct was introduced by electroporation into Raji cells, the B cell line which expresses HLA-DR. Expression of HLA-DR antigen was shown to be significantly suppressed in the stable transfectants.
This newly created construct presumably works to reduce the possibility of rejection by suppressing the HLA-DR expression of the transplanted graft.