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Tumor-specific CD4+ T cells develop cytotoxic activity and eliminate virus-induced tumor cells in the absence of regulatory T cells.

Akhmetzyanova I, Zelinskyy G, Schimmer S, Brandau S, Altenhoff P, Sparwasser T, Dittmer U - Cancer Immunol. Immunother. (2012)

Bottom Line: We show here that there is an expansion of tumor-specific CD4(+) T cells producing cytokines and cytotoxic molecule granzyme B (GzmB) in the early phase of tumor growth.Importantly, we demonstrate that in vivo depletion of regulatory T cells (Tregs) and CD8(+) T cells in FBL-3-bearing DEREG transgenic mice augments IL-2 and GzmB production by CD4(+) T cells and increases FV-specific CD4(+) T-cell effector and cytotoxic responses leading to the complete tumor regression.Therefore, the capacity to reject tumor acquired by tumor-reactive CD4(+) T cells largely depends on the direct suppressive activity of Tregs.

View Article: PubMed Central - PubMed

Affiliation: Institute for Virology, University of Duisburg-Essen, Virchowstr 179, 45147, Essen, Germany. ilseyar.akhmetzyanova@uni-due.de

ABSTRACT
The important role of tumor-specific cytotoxic CD8(+) T cells is well defined in the immune control of the tumors, but the role of effector CD4(+) T cells is poorly understood. In the current research, we have used a murine retrovirus-induced tumor cell line of C57BL/6 mouse origin, namely FBL-3 cells, as a model to study basic mechanisms of immunological control and escape during tumor formation. This study shows that tumor-specific CD4(+) T cells are able to protect against virus-induced tumor cells. We show here that there is an expansion of tumor-specific CD4(+) T cells producing cytokines and cytotoxic molecule granzyme B (GzmB) in the early phase of tumor growth. Importantly, we demonstrate that in vivo depletion of regulatory T cells (Tregs) and CD8(+) T cells in FBL-3-bearing DEREG transgenic mice augments IL-2 and GzmB production by CD4(+) T cells and increases FV-specific CD4(+) T-cell effector and cytotoxic responses leading to the complete tumor regression. Therefore, the capacity to reject tumor acquired by tumor-reactive CD4(+) T cells largely depends on the direct suppressive activity of Tregs. We suggest that a cytotoxic CD4(+) T-cell immune response may be induced to enhance resistance against oncovirus-associated tumors.

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Kinetics of FBL-3-specific effector CD4+ and CD8+ T-cell responses: B6 mice were inoculated s.c. with 1 × 107 FBL-3 cells (n = 9–12 mice per group). Mean percentages ± SEM of FBL-3-specific CD4+TetII+ T cells reactive with I-Ab MHC class II tetramers specific for FV-Env epitope (a) and effector CD8+ T cells reactive with MHC class I H-2Db tetramers specific for the FV gagL CTL epitope (b) in draining (white box plots) and non-draining (grey box plots) lymph nodes. The mean percentage for each group is indicated by a line. c Expansion of antigen-specific CD4 T cells in draining lymph nodes at day 4 ptc is shown. Each dot represents an individual mouse, and the mean numbers are indicated by a line. All tetramer-positive T cells expressed cell-surface activation marker CD43. Statistically significant differences between the groups are given in the figures. The experiment was repeated three times with comparable results
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Fig1: Kinetics of FBL-3-specific effector CD4+ and CD8+ T-cell responses: B6 mice were inoculated s.c. with 1 × 107 FBL-3 cells (n = 9–12 mice per group). Mean percentages ± SEM of FBL-3-specific CD4+TetII+ T cells reactive with I-Ab MHC class II tetramers specific for FV-Env epitope (a) and effector CD8+ T cells reactive with MHC class I H-2Db tetramers specific for the FV gagL CTL epitope (b) in draining (white box plots) and non-draining (grey box plots) lymph nodes. The mean percentage for each group is indicated by a line. c Expansion of antigen-specific CD4 T cells in draining lymph nodes at day 4 ptc is shown. Each dot represents an individual mouse, and the mean numbers are indicated by a line. All tetramer-positive T cells expressed cell-surface activation marker CD43. Statistically significant differences between the groups are given in the figures. The experiment was repeated three times with comparable results

Mentions: To study T-cell responses in tumor cell rejection, we used the leukemia cell line FBL-3, a FV-induced tumor line from a C57Bl/6 mouse. These highly immunogenic murine leukemia cells induce local tumor growth after s.c. injection into C57/Bl6 mice for about 20 days before being rejected due to IFN-γ and granzyme-producing CD8+ T cells [11]. It has been shown that FBL-3 tumor cells express FV antigens that can be recognized by CD8+ and CD4+ T cells [9, 10]. To determine the kinetics of T-cell responses in this tumor rejection model, we quantified the population of FV-specific effector CD8+ T cells by staining lymphocytes from draining (drLN) and non-draining lymph nodes (non-drLN) of FBL-3-challenged mice with H-2DbgagL MHC class I tetramers [9, 20] or MHC class II tetramers loaded with the H-2I-Ab-restricted CD4+ T-cell epitope H19-Env [20]. Early after tumor challenge (4 days post-tumor challenge (ptc)), expansion of specific cells was only found in the CD4+ but not the CD8+ T-cell population (Fig. 1a, b). Thus, the frequencies of antigen-specific CD4+ T cells in drLN at day 4 ptc were significantly higher compared to specific CD8+ T cells (Fig. 1c). Peak expansion of specific CD4+ T cells was found as early as at 6 days post-tumor challenge, whereas CD8+ T-cell expansion reached its maximum 2 days later (Fig. 1a, b). For both T-cell populations, the contraction phase began at day 15 ptc. A comparison between different lymph nodes showed that the specific CD4+ and CD8+ T-cell responses were generally located in drLN as the peak expansion of T cells was significantly higher in drLN than in non-drLN. However, a modest increase in the percentage of specific CD4+ and CD8+ T cells was also observed in non-drLN compared to lymph nodes cells from naïve animals (Fig. 1a, b). Collectively, the data demonstrate a local expansion of tumor-specific T cells with the CD4+ T-cell response developing more rapidly than the CD8+ T-cell response.Fig. 1


Tumor-specific CD4+ T cells develop cytotoxic activity and eliminate virus-induced tumor cells in the absence of regulatory T cells.

Akhmetzyanova I, Zelinskyy G, Schimmer S, Brandau S, Altenhoff P, Sparwasser T, Dittmer U - Cancer Immunol. Immunother. (2012)

Kinetics of FBL-3-specific effector CD4+ and CD8+ T-cell responses: B6 mice were inoculated s.c. with 1 × 107 FBL-3 cells (n = 9–12 mice per group). Mean percentages ± SEM of FBL-3-specific CD4+TetII+ T cells reactive with I-Ab MHC class II tetramers specific for FV-Env epitope (a) and effector CD8+ T cells reactive with MHC class I H-2Db tetramers specific for the FV gagL CTL epitope (b) in draining (white box plots) and non-draining (grey box plots) lymph nodes. The mean percentage for each group is indicated by a line. c Expansion of antigen-specific CD4 T cells in draining lymph nodes at day 4 ptc is shown. Each dot represents an individual mouse, and the mean numbers are indicated by a line. All tetramer-positive T cells expressed cell-surface activation marker CD43. Statistically significant differences between the groups are given in the figures. The experiment was repeated three times with comparable results
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Related In: Results  -  Collection

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Fig1: Kinetics of FBL-3-specific effector CD4+ and CD8+ T-cell responses: B6 mice were inoculated s.c. with 1 × 107 FBL-3 cells (n = 9–12 mice per group). Mean percentages ± SEM of FBL-3-specific CD4+TetII+ T cells reactive with I-Ab MHC class II tetramers specific for FV-Env epitope (a) and effector CD8+ T cells reactive with MHC class I H-2Db tetramers specific for the FV gagL CTL epitope (b) in draining (white box plots) and non-draining (grey box plots) lymph nodes. The mean percentage for each group is indicated by a line. c Expansion of antigen-specific CD4 T cells in draining lymph nodes at day 4 ptc is shown. Each dot represents an individual mouse, and the mean numbers are indicated by a line. All tetramer-positive T cells expressed cell-surface activation marker CD43. Statistically significant differences between the groups are given in the figures. The experiment was repeated three times with comparable results
Mentions: To study T-cell responses in tumor cell rejection, we used the leukemia cell line FBL-3, a FV-induced tumor line from a C57Bl/6 mouse. These highly immunogenic murine leukemia cells induce local tumor growth after s.c. injection into C57/Bl6 mice for about 20 days before being rejected due to IFN-γ and granzyme-producing CD8+ T cells [11]. It has been shown that FBL-3 tumor cells express FV antigens that can be recognized by CD8+ and CD4+ T cells [9, 10]. To determine the kinetics of T-cell responses in this tumor rejection model, we quantified the population of FV-specific effector CD8+ T cells by staining lymphocytes from draining (drLN) and non-draining lymph nodes (non-drLN) of FBL-3-challenged mice with H-2DbgagL MHC class I tetramers [9, 20] or MHC class II tetramers loaded with the H-2I-Ab-restricted CD4+ T-cell epitope H19-Env [20]. Early after tumor challenge (4 days post-tumor challenge (ptc)), expansion of specific cells was only found in the CD4+ but not the CD8+ T-cell population (Fig. 1a, b). Thus, the frequencies of antigen-specific CD4+ T cells in drLN at day 4 ptc were significantly higher compared to specific CD8+ T cells (Fig. 1c). Peak expansion of specific CD4+ T cells was found as early as at 6 days post-tumor challenge, whereas CD8+ T-cell expansion reached its maximum 2 days later (Fig. 1a, b). For both T-cell populations, the contraction phase began at day 15 ptc. A comparison between different lymph nodes showed that the specific CD4+ and CD8+ T-cell responses were generally located in drLN as the peak expansion of T cells was significantly higher in drLN than in non-drLN. However, a modest increase in the percentage of specific CD4+ and CD8+ T cells was also observed in non-drLN compared to lymph nodes cells from naïve animals (Fig. 1a, b). Collectively, the data demonstrate a local expansion of tumor-specific T cells with the CD4+ T-cell response developing more rapidly than the CD8+ T-cell response.Fig. 1

Bottom Line: We show here that there is an expansion of tumor-specific CD4(+) T cells producing cytokines and cytotoxic molecule granzyme B (GzmB) in the early phase of tumor growth.Importantly, we demonstrate that in vivo depletion of regulatory T cells (Tregs) and CD8(+) T cells in FBL-3-bearing DEREG transgenic mice augments IL-2 and GzmB production by CD4(+) T cells and increases FV-specific CD4(+) T-cell effector and cytotoxic responses leading to the complete tumor regression.Therefore, the capacity to reject tumor acquired by tumor-reactive CD4(+) T cells largely depends on the direct suppressive activity of Tregs.

View Article: PubMed Central - PubMed

Affiliation: Institute for Virology, University of Duisburg-Essen, Virchowstr 179, 45147, Essen, Germany. ilseyar.akhmetzyanova@uni-due.de

ABSTRACT
The important role of tumor-specific cytotoxic CD8(+) T cells is well defined in the immune control of the tumors, but the role of effector CD4(+) T cells is poorly understood. In the current research, we have used a murine retrovirus-induced tumor cell line of C57BL/6 mouse origin, namely FBL-3 cells, as a model to study basic mechanisms of immunological control and escape during tumor formation. This study shows that tumor-specific CD4(+) T cells are able to protect against virus-induced tumor cells. We show here that there is an expansion of tumor-specific CD4(+) T cells producing cytokines and cytotoxic molecule granzyme B (GzmB) in the early phase of tumor growth. Importantly, we demonstrate that in vivo depletion of regulatory T cells (Tregs) and CD8(+) T cells in FBL-3-bearing DEREG transgenic mice augments IL-2 and GzmB production by CD4(+) T cells and increases FV-specific CD4(+) T-cell effector and cytotoxic responses leading to the complete tumor regression. Therefore, the capacity to reject tumor acquired by tumor-reactive CD4(+) T cells largely depends on the direct suppressive activity of Tregs. We suggest that a cytotoxic CD4(+) T-cell immune response may be induced to enhance resistance against oncovirus-associated tumors.

Show MeSH
Related in: MedlinePlus