טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentEpel Malki
SubjectMolecular Strategies for Targeting and Studying MHC I
Presentation: Recombinant TCRs and TCR-like
Antibodies
DepartmentDepartment of Biology
Supervisor Professor Yoram Reiter


Abstract

The MHC/peptide complex holds a pivotal role in the study of anti-tumor cellular immune responses. Therefore, we aimed in this research to develop and use new immunological molecules to study antigen presentation by tumor cells.

To this end we produced and characterized two kinds of molecules: 1. T cell receptor (TCR)-based. 2. Antibody-based which mimic TCR specificity. For the first approach, we constructed two different TCR scFv molecules: a p53TCR scFv, and  a gp100TCR scFv. 

 We demonstrated for the first time that a Vα/Vβ scFv TCRs are capable to specifically target antigen-presenting cells as well as tumor cells  and kill them in an antigen (peptide)-specific manner. This was achieved by constructing a TCR scFv-Toxin fusion protein in which the TCR scFv fragment is fused to a truncated form of a very potent bacterial toxin, Pseudomonas exotoxin (PE).

For the second approach we isolated by phage display a panel of human recombinant Fab TCR-like antibodies directed toward novel TCRg Alternative Reading frame Protein (TARP) epitopes in complex with MHC class I molecule which is expressed on prostate and breast cancer cells. We have characterized one of these recombinant antibodies and demonstrated its capacity to recognize the native MHC-peptide complex expressed on the surface of APC as well as tumor cells.

Furthermore, by genetic fusion we armed the TCR-like antibody with a potent toxin and demonstrated that it can serve as a targeting moiety killing tumor cells in a peptide-specific, MHC-restricted manner similar to cytotoxic T-cell Lymphocytes.

 We have also shown that the recombinant TCR-like Fab fragment in its naked form or as IgG molecule can induce peptide-specific, MHC-restricted cell death.