Peptide repertoire of EBV+ tumor infiltrating B cells from a triple negative breast cancer patient

Abstract

The Epstein-Barr virus (EBV) is one of the most common human viruses and infects B cells as well as epithelial cells. Even though the relationship between EBV infection in B cells and several types of human lymphomas is well established, the involvement of EBV in human carcinomas such as breast cancer has been recently described and it is not fully understood. Recent studies are focused on the role of the EBV infection in the development and progression of carcinomas, but less data is available about the influence of the virus on tumor infiltrating lymphocytes (TILs). Thus, the main objectives of this project are (i) to describe the peptide repertoire of EBV-transformed B cells from TILs isolated from a triple negative breast cancer patient and (ii) to identify EBV-specific T cells isolated from the tumor site. An exhaustive study of TILs isolated from a triple negative breast cancer patient with a high B-cell infiltrate was performed. TILs were expanded directly from the biopsy. EBV-positive B cells from the tumor were directly obtained from a tumor-engrafted NOD/SCID mouse (PDX). These cells were then used as APCs to expand T cells from TILs. Furthermore, peptides presented by MHC were eluted from the PDX cells, followed by MS analysis. Specific T cells expanded with PDX cells were obtained, suggesting that the presence of EBV+ cells in the tumor microenvironment could be a modulating factor for the immune system.