טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentAltman Efrat
SubjectAntigen-Specific Immunomodulation for Multiple Sclerosis
Mediated by Recombinant Antibodies Recognizing
Auto-Reactive T Cell Epitope
DepartmentDepartment of Biology
Supervisor Professor Yoram Reiter
Full Thesis textFull thesis text - English Version


Abstract

Multiple Sclerosis (MS) is an autoimmune disease of the CNS. The disease is characterized by demyelination, axonal damage and a variety of neurological symptoms. The disease is triggered by presentation of myelin autoantigens on MHC class II molecules by antigen-presenting cells (APC). Among the autoantigens is the Myelin Oligodendrocyte Glycoprotein (MOG). The presentation of myelin antigens leads to activation of autoreactive CD4 T cells in the periphery. After their activation, the T cells express cell surface activation markers that facilitate their extravasation across the blood-brain barrier. Upon entering the CNS, the CD4 T cells are reactivated by myelin epitopes presented by local APCs, which lead to local inflammation and activation of macrophages and microglia and the secretion of soluble mediators that cause myelin damage.

The main goal of this study was to generate MS-specific, recombinant antibody with MHC-restricted, peptide-specific reactivity, termed T-Cell Receptor-Like (TCRL) antibodies. Our antibodies mimic the specificity of the CD4 autoreactive T-Cell receptor, while binding MHC class II/peptide complexes in an autoantigen peptide specific, MHC restricted manner.  These antibodies could be used as antigen- specific immunotherapeutic approach. Such approaches could promote the tolerance to MS antigens without generally weakening the immune system. Furthermore, it can be used as a valuable research tool to study presentation of autoimmune epitopes

We have cloned and purified a soluble recombinant HLA-DR2 molecule and loaded it with the MOG35-55 peptide. Then, we introduced the DR2/ MOG35-55 complexes to a phage display library in order to isolate the desire antibodies. The antibody clones isolated from the library screening were characterized with some of them exhibiting TCR like specificity, thus, their binding was dependent on both the DR2 and the MOG peptide for recognition. They were also able to bind native DR2/ MOG35-55 complexes as presented by APCs. Most significant, the DR2/MOG-specific TCRL antibody was capable to block the recognition between MOG35-55 pulsed DR2 positive APCs and their cognate T cell hybridoma and prevent their activation as measured by inhibition of IL-2 secretion.

In the future, the DR2/ MOG35-55 -specific TCRL antibody will be used for two major research directions; to induce antigen-specific tolerance in vivo, in the mouse model of MS (EAE) and to analyze MS epitope presentation.