Identification of novel immunogenic HLA-DR-restricted peptides from tumour-associated antigens

Rojas, J.-M., 2003. Identification of novel immunogenic HLA-DR-restricted peptides from tumour-associated antigens. PhD, Nottingham Trent University.

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CD4+ T cells play a central role in antitumour immunity; not only do they provide help for the development of CTL recognising tumour antigens but they can also enhance antitumour responses via indirect cytotoxic mechanisms at the tumour site. Since CD4+ T cells recognise the antigen in the form of peptides presented on MHC class II molecules, attention has been focused in the recent years on the identification of these peptides derived from tumour antigens. Therefore the aim of this study was to identify novel immunogenic peptides derived from tumour antigens where presentation was restricted to human MHC class II HLA-DR1 and/or HLA-DR4 molecules. The adopted strategy consisted in predicting peptides from the tumour antigens p53, gpl00 and bcr-abl(b3a2) using computer-assisted algorithms, and immunisation of HLA-DR1 transgenic mice with these peptides in order to assess their immunogenicity. Immunogenic peptides in transgenic mice were then tested in human in in vitro T cell sensitisation assays.

To determine peptide immunogenicity in mice, a method was optimised using the reported I-Ak-restricted peptides HEL46-61 and HEL119-132. This model was then successfully established in HLA-DR1 transgenic mice with the model peptide HA307- 319. Proliferative responses and IFN-γ production were observed when the splenocytes of HLA-DR1 transgenic mice were re-presented in vitro with the HA307-319 peptide used in immunisation. Dendritic cells (DC) were shown to be better antigen presenting cells (APC) than syngeneic splenocytes in proliferation assays; thus DC were subsequently used as APC in the all experiments. Further characterisation of DC, generated from bone marrow precursors by culture with GM-CSF, demonstrated that day 8 non-adherent cells matured with LPS were optimal for antigen presentation in this experimental setting. Immunisation of HLA-DR1 transgenic mice with predicted peptides from p53, gpl00 and bcr-ab1(b3a2) resulted in HLA-DR1-restricted responses for two novel p53 peptides (p5363-77 and p53108-122) and two bcr-ab1 peptides (bcr-ablGFK11 and bcr-ab1ATG18). Responses were also observed to two novel gpl00 peptides (gpl00194-208 and gpl00556-580). This study demonstrated that HLA-DR-restricted responses to novel peptides can be obtained in HLA-DR1 transgenic mice. Furthermore, proliferative responses to p5363-77 in a HLA-DRl+ donor, to gpl00566-580 in another HLA-DRl+ donor, and to p53108-122 in two HLA-DR4+ donors demonstrated that these peptides were also immunogenic in human assays. Collectively, these results indicated that peptide immunisation of HLA-DRl transgenic mice could facilitate the identification of novel immunogenic HLA-DR-restricted peptides from tumour antigens, that allow us to understand further the role of CD4+ in antitumour immunity and improve cancer immunotherapeutic strategies.

Item Type: Thesis
Creators: Rojas, J.-M.
Date: 2003
ISBN: 9781369316391
Divisions: Schools > School of Science and Technology
Record created by: Linda Sullivan
Date Added: 28 Sep 2020 14:52
Last Modified: 07 Sep 2023 10:21

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