Expression of Tumour-Associated Antigens and Characteristics of T Cell Responses in Breast Carcinoma
Breast cancer is the most common cancer among women in Malaysia. The standard conventional clinical management procedures use chemotherapy, radiotherapy and mastectomy. In the past decade, intense research towards the use of T-cell based immunotherapy as a treatment alternative has been made. The...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English |
| Published: |
2005
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/6330/1/FPSK%28M%29_2005_8.pdf |
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| Summary: | Breast cancer is the most common cancer among women in Malaysia. The standard
conventional clinical management procedures use chemotherapy, radiotherapy and
mastectomy. In the past decade, intense research towards the use of T-cell based
immunotherapy as a treatment alternative has been made. The goals of our study are
first to identify some of the tumour-associated antigens present in our tumour
specimens from patients with infiltrating ductal carcinoma (IDC) of the breast,
followed by antigenic peptide selection in order to develop an in vitro T-cell based
cytotoxicity assay. At the same time, we also identified immunophenotypes of the
tumour infiltrating lymphocytes (TILs) in the breast tumours. Isolated peripheral
blood mononuclear cells (PBMCs) from patients with IDC were specifically
stimulated with three combinations of cytokines and antibodies that were specific to
the co-stimulatory molecule and HLA-A02 restricted antigen-specific peptides.
Stimulated PBMCs were then used as effector cells in cytotoxicity assay using
calcein-AM in which the MCF-7 breast adenocarcinoma cell line served as the target
cells. Phenotypic investigation of tumour cell suspension was carried out by using
specific lymphocyte cell differentiation markers. By using paraffin-embedded breast
tissues (n=49), immunohistochemistry studies showed significant expression of
survivin (8O.l%, p<0.00 I), cytoplasmic MUC- 1 (38.3%, p<0.05) and membranous
MUC-1 (63.8%, p<0.001) in the tumour area as compared to the apparently normal
adjacent tissues. These results provided a guide for antigenic peptide selection for
stimulating the T cells from the blood of the patients. Together in the presence of
rIL-2 and rIL-7, 4 out of 9 peripheral blood mononuclear cells (PBMCs) from the
patients responded to either survivin-derived peptide (S2) or Her21neu specific
peptide (H2) in a HLA-A02 restricted manner in order to produce sufficient amounts
of effector cells for the subsequent cytotoxic assay. As effectorltarget (EIT) ratio
increased, cytolytic activity of the effector cells became more efficient. For
immunophenotypic analysis, CD8+ TILs at 23.4 -t- 2.1% was found to be the major
population in TILs and the presence of its effector counterpart, CD8+CD28+ TILs
significantly correlated with low incidence of metastasis (p<0.05). At the same time,
we noticed the predominance of CD4+CD25+ regulatory T cells (Treg) at 55.9 +
3.9% in the Treg pool and its presence was significantly found in post-menopausal
patients @<0.05). In conclusion, survivin and MUC-1 (cytoplasmic and
membranous) were over-expressed in breast cancer tissues. Further investigations
are needed to determine the reasons as to why only a portion of PBMCs from the
patients (419) responded to the specific peptide-based stimulation and showed
effective cytolytic activity towards the target breast adenocarcinoma MCF-7 cell line.
It is possible that other cytokine cocktails are needed to enhance the cytolytic
property of the PBMCs. We also found that infiltration of effector TILs,
CD8+CD28+, significantly reduced the metastatic event. Lastly, we noted that older
women (2 50 years old) tend to possess higher amount of CD4+CD25+ Treg in TILs
as compared to the younger patients (< 50 years old). The higher CD4+CD5+ Treg
in Til may implicate poor disease outcome in older patients. We proposed that
these Treg cells contribute to tumour escape mechanism. |
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