Vujanovic, Lazar Nikola
(2006)
Promoting Type-1 CD4+ T Cell Immune Responses Against Tumor-Associated Antigen MAGE-A6.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
One of the main challenges facing tumor immunologists is to develop strategies that would effectively stimulate Type-1 anti-tumor T cell responses, which have been correlated with better clinical outcome and prolonged survival of cancer patients. As CD4+ T cells were shown to play a critical role in mediating these responses, it was of interest to examine novel ways of effectively stimulating and enhancing Type-1 CD4+ T cell responses. For these studies I used MAGE-A6, a tumor associated antigen (TAA) expressed by a broad range of human cancer types. Two novel MAGE-A6 T-helper epitopes were identified and were shown to be recognized by CD4+ T cells isolated from the majority of normal donors or patients with melanoma, regardless of their HLA genotype (i.e. poly-DR presented epitopes). Furthermore, peptide-specific T cells also recognized autologous monocytes pulsed with recombinant MAGE-A6 protein, supporting the natural processing and MHC presentation of these epitopes. Interestingly, one of the novel MAGE-A6 epitopes possesses a high-degree of homology with a microbial peptide. CD4+ T cells stimulated in vitro with this microbial peptide cross-reacted against the MAGE-A6 homologue peptide, and could recognize naturally-processed MAGE-A6 epitopes more effectively than T cells stimulated with MAGE-A6 peptides. This study showed that it is possible to stimulate, and even enhance tumor-specific T cell responses using microbial epitopes that are homologous to TAA-derived peptides. In the final study, human dendritic cells (DC) were engineered to secrete high levels of IFN-ƒ×-inducing cytokines IL-12p70 and IL-18 via recombinant adenoviral infection to generate an in vitro stimulus capable of promoting previously deficient patient Th1-type responses. DC engineered to secrete both of these cytokines simultaneously (DC.IL-12/18) were highly effective at stimulating MAGE-A6-specific Th1-type CD4+ T cell responses from patients with melanoma, particularly when loaded with MAGE-A6 protein. Poly-DR presented epitopes and MAGE-A6 protein defined in this thesis, if loaded onto DC.IL-12/18, could prove clinically useful as a vaccine modality capable of promoting the recovery and/or enhancement of tumor antigen-specific, Th1-type CD4+ T cell responses in the majority of patients harboring MAGE-A6+ cancers.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
| Creators | Email | Pitt Username | ORCID  |
|---|
| Vujanovic, Lazar Nikola | lnvst3@pitt.edu | LNVST3 | |
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| ETD Committee: |
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| Date: |
29 June 2006 |
| Date Type: |
Completion |
| Defense Date: |
26 May 2006 |
| Approval Date: |
29 June 2006 |
| Submission Date: |
22 June 2006 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Immunology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
CD4+ T lymphocytes; Dendritic cells; gene therapy; MAGE-A6; peptide |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-06222006-141321/, etd-06222006-141321 |
| Date Deposited: |
10 Nov 2011 19:48 |
| Last Modified: |
19 Dec 2016 14:36 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/8164 |
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