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Self antigens expressed by solid tumors Do not efficiently stimulate naive or activated T cells: implications for immunotherapy.

Speiser DE, Miranda R, Zakarian A, Bachmann MF, McKall-Faienza K, Odermatt B, Hanahan D, Zinkernagel RM, Ohashi PS - J. Exp. Med. (1997)

Bottom Line: No significant spontaneous CTL activation against GP was observed.The data show that the tumor did not spontaneously induce or maintain an activated CTL response, revealing a profound lack of immunogenicity in vivo.Therefore, repetitive immunizations are necessary for prolonged antitumor immunotherapy.

View Article: PubMed Central - PubMed

Affiliation: Ontario Cancer Institute, Department of Medical Biophysics and Department of Immunology, University of Toronto, Ontario M5G 2M9, Canada.

ABSTRACT
Induction and maintenance of cytotoxic T lymphocyte (CTL) activity specific for a primary endogenous tumor was investigated in vivo. The simian virus 40 T antigen (Tag) expressed under the control of the rat insulin promoter (RIP) induced pancreatic beta-cell tumors producing insulin, causing progressive hypoglycemia. As an endogenous tumor antigen, the lymphocytic choriomeningitis virus (LCMV) glycoprotein (GP) was introduced also under the control of the RIP. No significant spontaneous CTL activation against GP was observed. However, LCMV infection induced an antitumor CTL response which efficiently reduced the tumor mass, resulting in temporarily normalized blood glucose levels and prolonged survival of double transgenic RIP(GP x Tag2) mice (137 +/- 18 d) as opposed to control RIP-Tag2 mice (88 +/- 8 d). Surprisingly, the tumor-specific CTL response was not sustained despite the facts that the tumor cells continued to express MHC class I and LCMV-GP-specific CTLs were present and not tolerized. Subsequent adoptive transfer of virus activated spleen cells into RIP(GP x Tag2) mice further prolonged survival (168 +/- 11 d), demonstrating continued expression of the LCMV-GP tumor antigen and MHC class I. The data show that the tumor did not spontaneously induce or maintain an activated CTL response, revealing a profound lack of immunogenicity in vivo. Therefore, repetitive immunizations are necessary for prolonged antitumor immunotherapy. In addition, the data suggest that the risk for induction of chronic autoimmune diseases is limited, which may encourage immunotherapy against antigens selectively but not exclusively expressed by the tumor.

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GP-specific T cells were neither spontaneously activated nor rendered unresponsive by the tumor. (A) LCMV-GP–specific proliferative responses. Spleen cells were taken from untreated mice (closed bars), 8 d after LCMV infection (open bars), or 30 d after LCMV infection (hatched bars) and incubated in vitro with stimulator macrophages treated with the LCMV glycoprotein peptide p33. Data are mean ± SD of triplicate cultures. Control cultures using macrophages without peptide had background levels <3,000 cpm (not shown). (B–E) Normal LCMV-specific cytotoxic responses were  detected 8 d after LCMV infection (B and C), or 30 d after LCMV infection upon restimulation in vitro for 5 d (D and E). In the RIP(GP × Tag2) mice  studied 30 d after LCMV infection the tumors had grown back and blood glucose was low (3–5 mM). No data were obtained for day 30 RIP-GP or  RIP-Tag2 mice (n.d., not determined) because these animals were killed due to diabetes or tumor burden. Target cells were MC57G fibroblasts untreated (C and E) or treated with peptide p33 (B and D). The results shown are representative for three independent experiments and analysis of at least  four mice per group. ▪, RIP-GP; •, RIP(GP × Tag2); ○, RIP-Tag2; □, C57BL/6.
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Figure 2: GP-specific T cells were neither spontaneously activated nor rendered unresponsive by the tumor. (A) LCMV-GP–specific proliferative responses. Spleen cells were taken from untreated mice (closed bars), 8 d after LCMV infection (open bars), or 30 d after LCMV infection (hatched bars) and incubated in vitro with stimulator macrophages treated with the LCMV glycoprotein peptide p33. Data are mean ± SD of triplicate cultures. Control cultures using macrophages without peptide had background levels <3,000 cpm (not shown). (B–E) Normal LCMV-specific cytotoxic responses were detected 8 d after LCMV infection (B and C), or 30 d after LCMV infection upon restimulation in vitro for 5 d (D and E). In the RIP(GP × Tag2) mice studied 30 d after LCMV infection the tumors had grown back and blood glucose was low (3–5 mM). No data were obtained for day 30 RIP-GP or RIP-Tag2 mice (n.d., not determined) because these animals were killed due to diabetes or tumor burden. Target cells were MC57G fibroblasts untreated (C and E) or treated with peptide p33 (B and D). The results shown are representative for three independent experiments and analysis of at least four mice per group. ▪, RIP-GP; •, RIP(GP × Tag2); ○, RIP-Tag2; □, C57BL/6.

Mentions: It was important to directly examine the GP-specific T cell responses by the tumor-bearing mice. Spleen cells were stimulated with irradiated macrophages pulsed with peptide p33, the major epitope of LCMV-GP in the H-2b haplotype (30). Fig. 2 A (closed bars) shows that the T cells from untreated RIP-GP, RIP-Tag2, and double transgenic mice did not proliferate significantly. Proliferation could be observed in spleen cells derived from mice transgenic for a GP-specific TCR. Because this assay can easily detect GP-specific memory CTLs from LCMV-immunized C57BL/6 mice (see below), the results indicated that no efficient spontaneous lymphocyte activation against the LCMV-GP tumor antigen had occurred in vivo (23, 24).


Self antigens expressed by solid tumors Do not efficiently stimulate naive or activated T cells: implications for immunotherapy.

Speiser DE, Miranda R, Zakarian A, Bachmann MF, McKall-Faienza K, Odermatt B, Hanahan D, Zinkernagel RM, Ohashi PS - J. Exp. Med. (1997)

GP-specific T cells were neither spontaneously activated nor rendered unresponsive by the tumor. (A) LCMV-GP–specific proliferative responses. Spleen cells were taken from untreated mice (closed bars), 8 d after LCMV infection (open bars), or 30 d after LCMV infection (hatched bars) and incubated in vitro with stimulator macrophages treated with the LCMV glycoprotein peptide p33. Data are mean ± SD of triplicate cultures. Control cultures using macrophages without peptide had background levels <3,000 cpm (not shown). (B–E) Normal LCMV-specific cytotoxic responses were  detected 8 d after LCMV infection (B and C), or 30 d after LCMV infection upon restimulation in vitro for 5 d (D and E). In the RIP(GP × Tag2) mice  studied 30 d after LCMV infection the tumors had grown back and blood glucose was low (3–5 mM). No data were obtained for day 30 RIP-GP or  RIP-Tag2 mice (n.d., not determined) because these animals were killed due to diabetes or tumor burden. Target cells were MC57G fibroblasts untreated (C and E) or treated with peptide p33 (B and D). The results shown are representative for three independent experiments and analysis of at least  four mice per group. ▪, RIP-GP; •, RIP(GP × Tag2); ○, RIP-Tag2; □, C57BL/6.
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Related In: Results  -  Collection

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Figure 2: GP-specific T cells were neither spontaneously activated nor rendered unresponsive by the tumor. (A) LCMV-GP–specific proliferative responses. Spleen cells were taken from untreated mice (closed bars), 8 d after LCMV infection (open bars), or 30 d after LCMV infection (hatched bars) and incubated in vitro with stimulator macrophages treated with the LCMV glycoprotein peptide p33. Data are mean ± SD of triplicate cultures. Control cultures using macrophages without peptide had background levels <3,000 cpm (not shown). (B–E) Normal LCMV-specific cytotoxic responses were detected 8 d after LCMV infection (B and C), or 30 d after LCMV infection upon restimulation in vitro for 5 d (D and E). In the RIP(GP × Tag2) mice studied 30 d after LCMV infection the tumors had grown back and blood glucose was low (3–5 mM). No data were obtained for day 30 RIP-GP or RIP-Tag2 mice (n.d., not determined) because these animals were killed due to diabetes or tumor burden. Target cells were MC57G fibroblasts untreated (C and E) or treated with peptide p33 (B and D). The results shown are representative for three independent experiments and analysis of at least four mice per group. ▪, RIP-GP; •, RIP(GP × Tag2); ○, RIP-Tag2; □, C57BL/6.
Mentions: It was important to directly examine the GP-specific T cell responses by the tumor-bearing mice. Spleen cells were stimulated with irradiated macrophages pulsed with peptide p33, the major epitope of LCMV-GP in the H-2b haplotype (30). Fig. 2 A (closed bars) shows that the T cells from untreated RIP-GP, RIP-Tag2, and double transgenic mice did not proliferate significantly. Proliferation could be observed in spleen cells derived from mice transgenic for a GP-specific TCR. Because this assay can easily detect GP-specific memory CTLs from LCMV-immunized C57BL/6 mice (see below), the results indicated that no efficient spontaneous lymphocyte activation against the LCMV-GP tumor antigen had occurred in vivo (23, 24).

Bottom Line: No significant spontaneous CTL activation against GP was observed.The data show that the tumor did not spontaneously induce or maintain an activated CTL response, revealing a profound lack of immunogenicity in vivo.Therefore, repetitive immunizations are necessary for prolonged antitumor immunotherapy.

View Article: PubMed Central - PubMed

Affiliation: Ontario Cancer Institute, Department of Medical Biophysics and Department of Immunology, University of Toronto, Ontario M5G 2M9, Canada.

ABSTRACT
Induction and maintenance of cytotoxic T lymphocyte (CTL) activity specific for a primary endogenous tumor was investigated in vivo. The simian virus 40 T antigen (Tag) expressed under the control of the rat insulin promoter (RIP) induced pancreatic beta-cell tumors producing insulin, causing progressive hypoglycemia. As an endogenous tumor antigen, the lymphocytic choriomeningitis virus (LCMV) glycoprotein (GP) was introduced also under the control of the RIP. No significant spontaneous CTL activation against GP was observed. However, LCMV infection induced an antitumor CTL response which efficiently reduced the tumor mass, resulting in temporarily normalized blood glucose levels and prolonged survival of double transgenic RIP(GP x Tag2) mice (137 +/- 18 d) as opposed to control RIP-Tag2 mice (88 +/- 8 d). Surprisingly, the tumor-specific CTL response was not sustained despite the facts that the tumor cells continued to express MHC class I and LCMV-GP-specific CTLs were present and not tolerized. Subsequent adoptive transfer of virus activated spleen cells into RIP(GP x Tag2) mice further prolonged survival (168 +/- 11 d), demonstrating continued expression of the LCMV-GP tumor antigen and MHC class I. The data show that the tumor did not spontaneously induce or maintain an activated CTL response, revealing a profound lack of immunogenicity in vivo. Therefore, repetitive immunizations are necessary for prolonged antitumor immunotherapy. In addition, the data suggest that the risk for induction of chronic autoimmune diseases is limited, which may encourage immunotherapy against antigens selectively but not exclusively expressed by the tumor.

Show MeSH
Related in: MedlinePlus