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Specific cytotoxic T lymphocytes in gene therapy
U Altenschmidt1, D Moritz, B Groner
1Institute for Experimental Cancer Research, Tumor Biology Center, Freiburg, Germany.
Abstract:
Cytotoxic T lymphocytes possess the capacity to lyse target cells which express antigens on their surface recognized by the T cell receptor. These cells are crucial in the body's defense against foreign antigens. It has long been a goal of tumor biology to utilize T cells specialized in the elimination of unwanted cells for the treatment of cancer. The killing activity of T lymphocytes is restricted to specific antigen-presenting cells. For this reason the use of cytotoxic T cells in the elimination of cancer cells is limited to cancer cells which present neoantigens on their surface. To circumvent this limitation we describe a procedure in which the zeta component of the T cell receptor is genetically manipulated and equipped with an extracellular recognition domain. Introduction of a chimeric gene, consisting of the zeta chain of the T cell receptor and a single-chain antibody domain, into cytotoxic T lymphocytes results in T cells with a predetermined recognition specificity for particular tumor cells. The MHC restriction of target cell recognition can be avoided and tumor cells recognized by the single chain antibody domain can be recognized and lysed. Retroviral-mediated gene transduction was used to introduce chimeric zeta chain constructs into primary T cells of mice. The cocultivation of retrovirus producing helper cells with in vitro activated T lymphocytes led to a high gene transduction efficiency into primary T cells. These primary T cells assumed a predetermined specificity for target cell recognition and lysis. The production and provision of tumor cell specific T lymphocytes might not be sufficient to eradicate large tumors in vivo. Using a Schwannoma cell line, we showed that transplanted tumors secrete transforming growth factor beta and thereby stifle the action of lymphocytes. We suggest that a coordinated strategy including the suppression of tumor cells specific antilymphocyte action and the provision of tumor cell specific T cells might be required to successfully eliminate tumor cells in vivo.
Insights
Genetically engineered T cells can target specific tumor cells by incorporating a chimeric zeta chain, overcoming limitations of natural T cell recognition for cancer therapy. Further strategies are needed to overcome tumor-induced immunosuppression for effective in vivo eradication.
Area of Science:
- Immunology
- Cancer Biology
- Genetic Engineering
Background:
- Cytotoxic T lymphocytes (CTLs) are crucial for recognizing and eliminating target cells expressing specific antigens via their T cell receptor (TCR).
- The therapeutic application of CTLs in cancer treatment is limited by their requirement to recognize tumor-specific antigens presented by MHC molecules.
- Tumor cells can evade immune detection and destruction through various mechanisms, including the secretion of immunosuppressive factors.
Purpose of the Study:
- To engineer CTLs with predetermined specificity for tumor cells, circumventing MHC restriction.
- To investigate the efficacy of genetically modified CTLs in recognizing and lysing target tumor cells.
- To explore strategies for overcoming tumor-induced immunosuppression to enhance in vivo anti-tumor immunity.
Main Methods:
- Genetic manipulation of the zeta component of the TCR to include an extracellular single-chain antibody domain, creating a chimeric zeta chain.
- Retroviral-mediated gene transduction to introduce chimeric zeta chain constructs into primary mouse T cells.
- Co-cultivation of engineered T cells with tumor cells and assessment of target cell recognition and lysis, including evaluation of tumor-secreted immunosuppressive factors.
Main Results:
- High gene transduction efficiency was achieved, resulting in primary T cells with engineered specificity for target cell recognition and lysis.
- The engineered T cells demonstrated the ability to recognize and lyse tumor cells independent of MHC restriction.
- Tumors were shown to secrete transforming growth factor beta (TGF-β), which suppresses lymphocyte activity.
Conclusions:
- Genetically engineered T cells expressing chimeric zeta chains can be endowed with predetermined specificity for tumor cells, offering a potential cancer immunotherapy approach.
- Overcoming MHC restriction broadens the applicability of T cell-based cancer therapy.
- A combination of engineered T cells and strategies to counteract tumor-induced immunosuppression, such as inhibiting TGF-β, is likely necessary for effective in vivo tumor eradication.