Biomedical subjects

Yasuharu Nishimura

Publications and source records attributed to Yasuharu Nishimura.

At least 19 recordsLinked to original sources

PubMed2007

Involvement of regulatory T cells in the experimental autoimmune encephalomyelitis-preventive effect of dendritic cells expressing myelin oligodendrocyte glycoprotein plus TRAIL.

We previously reported the protection from myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) by the adoptive transfer of genetically modified embryonic stem cell-derived dendritic cells (ES-DC) presenting MOG peptide in the context of MHC class II molecules and simultaneously expressing TRAIL (ES-DC-TRAIL/MOG). In the present study, we found the severity of EAE induced by another myelin autoantigen, myelin basic protein, was also decreased after treatment with ES-DC-TRAIL/MOG. This preventive effect diminished, if the function of CD4(+)CD25(+) regulatory T cells (Treg) was abrogated by the injection of anti-CD25 mAb into mice before treatment with ES-DC-TRAIL/MOG. The adoptive transfer of CD4(+)CD25(+) T cells from ES-DC-TRAIL/MOG-treated mice protected the recipient mice from MOG- or myelin basic protein-induced EAE. The number of Foxp3(+) cells increased in the spinal cords of mice treated with ES-DC-TRAIL/MOG. In vitro experiments showed that TRAIL expressed in genetically modified ES-DC and also in LPS-stimulated splenic macrophages had a capacity to augment the proliferation of CD4(+)CD25(+) T cells. These results suggest that the prevention of EAE by treatment with ES-DC-TRAIL/MOG is mediated, at least in part, by MOG-reactive CD4(+)CD25(+) Treg propagated by ES-DC-TRAIL/MOG. For the treatment of organ-specific autoimmune diseases, induction of Treg reactive to the organ-specific autoantigens by the transfer of DC-presenting Ags and simultaneously overexpressing TRAIL therefore appears to be a promising strategy.

Adoptive Transfer↗

PubMed2006

Protein kinase D2 contributes to either IL-2 promoter regulation or induction of cell death upon TCR stimulation depending on its activity in Jurkat cells.

Members of protein kinase D (PKD) family serine/threonine kinases (PKD1, PKD2 and PKD3) are expressed in wide range of cells and regulate various cellular responses including immune responses. We have previously shown that PKD is involved in the signaling pathways of a human CD4(+) T cell clone stimulated with its cognate antigen. Contrary to foregoing publications, PKD1 mRNA was not detected in human T cells, Jurkat cells and mouse thymocytes and splenocytes. Instead, mass-spectrometric and reverse transcription-PCR analyses revealed that PKD2 was predominant in T cells. To investigate the roles of PKD2, wild-type (WT) and constitutively active (CA) PKD2 were expressed in Jurkat cells together with IL-2 promoter-driven reporter gene. Expression of WT-PKD2 enhanced IL-2 promoter activity upon stimulation with anti-CD3 mAb, while expression of CA-PKD2 inhibited IL-2 promoter activity and induced cell death. Although the cell death was suppressed by the treatment with caspase inhibitor, the IL-2 promoter activity was rarely recovered in CA-PKD2-expressing cells upon TCR stimulation. WT-PKD2 localized mainly in the cytoplasm translocated into the nucleus after TCR stimulation, while CA-PKD2 was present in both the cytoplasm and the nuclei before and after stimulation. Proteomic analyses revealed that CA-PKD2 enhanced the amount of phosphorylated SET protein, a histone chaperon that regulates histone acetylation, in Jurkat cells and the recombinant SET protein was phosphorylated by CA-PKD2 in vitro. The data provide a renewing insight into the subset of PKD family kinases expressed in T cells and suggest that PKD2 is involved in IL-2 promoter regulation and cell death depending on its activity upon TCR stimulation.

Animals↗

PubMed2006

Identification of HLA-A2- or HLA-A24-restricted CTL epitopes possibly useful for glypican-3-specific immunotherapy of hepatocellular carcinoma.

PURPOSE AND EXPERIMENTAL DESIGN: We previously reported that glypican-3 (GPC3) was overexpressed, specifically in hepatocellular carcinoma (HCC) and melanoma in humans, and it was useful as a novel tumor marker. We also reported that the preimmunization of BALB/c mice with dendritic cells pulsed with the H-2K(d)-restricted mouse GPC3(298-306) (EYILSLEEL) peptide prevented the growth of tumor-expressing mouse GPC3. Because of similarities in the peptide binding motifs between H-2K(d) and HLA-A24 (A*2402), the GPC3(298-306) peptide therefore seemed to be useful for the immunotherapy of HLA-A24+ patients with HCC and melanoma. In this report, we investigated whether the GPC3(298-306) peptide could induce GPC3-reactive CTLs from the peripheral blood mononuclear cells (PBMC) of HLA-A24 (A*2402)+ HCC patients. In addition, we used HLA-A2.1 (HHD) transgenic mice to identify the HLA-A2 (A*0201)-restricted GPC3 epitopes to expand the applications of GPC3-based immunotherapy to the HLA-A2+ HCC patients. RESULTS: We found that the GPC3(144-152) (FVGEFFTDV) peptide could induce peptide-reactive CTLs in HLA-A2.1 (HHD) transgenic mice without inducing autoimmunity. In five out of eight HLA-A2+ GPC3+ HCC patients, the GPC3(144-152) peptide-reactive CTLs were generated from PBMCs by in vitro stimulation with the peptide and the GPC3(298-306) peptide-reactive CTLs were also generated from PBMCs in four of six HLA-A24+ GPC3+ HCC patients. The inoculation of these CTLs reduced the human HCC tumor mass implanted into nonobese diabetic/severe combined immunodeficiency mice. CONCLUSION: Our study raises the possibility that these GPC3 peptides may therefore be applicable to cancer immunotherapy for a large number of HCC patients.

Amino Acid Sequence↗

PubMed2006

Immunization with heat shock protein 105-pulsed dendritic cells leads to tumor rejection in mice.

Recently, we reported that heat shock protein 105 (HSP105) DNA vaccination induced anti-tumor immunity. In this study, we set up a preclinical study to investigate the usefulness of dendritic cells (DCs) pulsed with mouse HSP105 as a whole protein for cancer immunotherapy in vivo. The recombinant HSP105 did not induce DC maturation, and the mice vaccinated with HSP105-pulsed BM-DCs were markedly prevented from the growth of subcutaneous tumors, accompanied with a massive infiltration of both CD4+ T cells and CD8+ T cells into the tumors. In depletion experiments, we proved that both CD4+ T cells and CD8+ T cells play a crucial role in anti-tumor immunity. Both CD4+ T cells and CD8+ T cells specific to HSP105 were induced by stimulation with HSP105-pulsed DCs. As a result, vaccination of mice with BM-DCs pulsed with HSP105 itself could elicit a stronger tumor rejection in comparison to DNA vaccination.

Adoptive Transfer↗

PubMed2006

Embryonic stem cell-derived dendritic cells expressing glypican-3, a recently identified oncofetal antigen, induce protective immunity against highly metastatic mouse melanoma, B16-F10.

We have recently established a method to generate dendritic cells from mouse embryonic stem cells. By introducing exogenous genes into embryonic stem cells and subsequently inducing differentiation to dendritic cells (ES-DC), we can now readily generate transfectant ES-DC expressing the transgenes. A previous study revealed that the transfer of genetically modified ES-DC expressing a model antigen, ovalbumin, protected the recipient mice from a challenge with an ovalbumin-expressing tumor. In the present study, we examined the capacity of ES-DC expressing mouse homologue of human glypican-3, a recently identified oncofetal antigen expressed in human melanoma and hepatocellular carcinoma, to elicit protective immunity against glypican-3-expressing mouse tumors. CTLs specific to multiple glypican-3 epitopes were primed by the in vivo transfer of glypican-3-transfectant ES-DC (ES-DC-GPC3). The transfer of ES-DC-GPC3 protected the recipient mice from subsequent challenge with B16-F10 melanoma, naturally expressing glypican-3, and with glypican-3-transfectant MCA205 sarcoma. The treatment with ES-DC-GPC3 was also highly effective against i.v. injected B16-F10. No harmful side effects, such as autoimmunity, were observed for these treatments. The depletion experiments and immunohistochemical analyses suggest that both CD8+ and CD4+ T cells contributed to the observed antitumor effect. In conclusion, the usefulness of glypican-3 as a target antigen for antimelanoma immunotherapy was thus shown in the mouse model using the ES-DC system. Human dendritic cells expressing glypican-3 would be a promising means for therapy of melanoma and hepatocellular carcinoma.

Animals↗

PubMed2006

A role of kinase inactive ZAP-70 in altered peptide ligand stimulated T cell activation.

T cell activation signals induced by altered peptide ligands (APLs) are different from those induced by the original agonistic peptide. The characteristics of the former are partial phosphorylation of TCR-zeta and no tyrosine-phosphorylation of zeta-associated protein-70 (ZAP-70). To analyze further those signaling pathways, we introduced a dominant negative (DN) form of ZAP-70 into a human CD4(+) T cell clone in which fully and partially agonistic peptide ligands have been well characterized. We found that some over-expressed partially agonistic ligands (OPALs) induced T cell responses without tyrosine-phosphorylation and kinase activation of ZAP-70. However, those responses were inhibited in T cells expressing DN ZAP-70, which could associate with partially phosphorylated TCR-zeta. In OPAL-stimulated T cells, PLC-gamma1 was phosphorylated and it was suppressed by DN ZAP-70 expression, suggesting that the ZAP-70-TCR-zeta association mediates the activation of PLC-gamma1 leading to T cell responses even in the absence of kinase activation of ZAP-70.

CD4-Positive T-Lymphocytes↗

PubMed2006

TCR ligand avidity determines the mode of B-Raf/Raf-1/ERK activation leading to the activation of human CD4+ T cell clone.

The interactions between peptide/MHC complexes and their cognate TCR are essential for various T cell responses. However, the relationship between the avidity of TCR ligand and the subsequent intracellular signaling through the TCR is still unclear. To investigate the effects of TCR ligand avidity on TCR-mediated signaling, we established L cells expressing HLA-DR4 molecules covalently linked with agonistic peptide (high-affinity ligand) or altered peptide ligand (APL; low-affinity ligand) at various densities as APC for a cognate human CD4(+) T cell clone. Using this system, we demonstrated that the T cell clone stimulated with APL/HLA-DR4 complexes presented at an excessive density provoked the up-regulation of CD69, IL-2 production and proliferation, but no detectable phosphorylation of ZAP-70/LAT/SLP-76. Furthermore, in contrast to the high-affinity stimulation, the low-affinity stimulation evoked delayed and sustained activation of the B-Raf/extracellular signal-regulated kinase (ERK) pathway without Raf-1 activation. The strength and duration of B-Raf/ERK activations closely correlated with the density of the TCR ligand. A knockdown approach confirmed that B-Raf activation was indispensable for the APL-induced T cell responses. These observations suggest that the differences in TCR-peptide/MHC interactions reflect the strength and duration of B-Raf/Raf-1/ERK activation in the human CD4(+) T cells.

Amino Acid Sequence↗

PubMed2006

Altered peptide ligands control type II collagen-reactive T cells from rheumatoid arthritis patients.

We previously reported that peripheral blood mononuclear cells from HLA-DRB1*0101 Japanese patients with rheumatoid arthritis (RA) were highly reactive to 256-271 peptide of type II collagen (CII). In this report, we tried to regulate the CII reactivity of T cells from RA patients with HLA-DRB1*0101 by altered peptide ligand (APL), which is a single amino acid substitution of the T-cell epitope on CII 256-271 peptide. Antagonistic activity of 21 APLs was assessed using three different T-cell lines. Results showed that 262 (G-->A) APL of CII 256-271 exhibited antagonistic activity in all T-cell lines and it was suggested that the application of CII APL might be a new therapeutic strategy in the regulation of RA.

Amino Acid Sequence↗

PubMed2006

Synthetic small interfering RNA targeting heat shock protein 105 induces apoptosis of various cancer cells both in vitro and in vivo.

We previously reported that heat shock protein 105 (HSP105), identified by serological analysis of a recombinant cDNA expression library (SEREX) using serum from a pancreatic cancer patient, was overexpressed in various human tumors and in the testis of adult men by immunohistochemical analysis. In the present study, to elucidate the biological function of the HSP105 protein in cancer cells, we first established NIH3T3 cells overexpressing murine HSP105 (NIH3T3-HSP105). The NIH3T3-HSP105 cells acquired resistance to apoptosis induced by heat shock or doxorubicin. The small interfering RNA (siRNA)-mediated suppression of HSP105 protein expression induced apoptosis in human cancer cells but not in fibroblasts. By a combination of siRNA introduction and doxorubicin or heat shock treatment, apoptosis was induced synergistically in a human colon cancer cell line, HCT116. In vivo, siRNA inoculation into the human gastric cancer cell line KATO-3 established in the flank of an NOD SCID mouse suppressed the tumor growth. This siRNA-induced apoptosis was mediated through caspases, but not the p53 tumor suppressor protein, even though the HSP105 protein was bound to wild-type p53 protein in HCT116 cells. These findings suggest that the constitutive overexpression of HSP105 in cancer cells is involved in malignant transformation by protecting tumor cells from apoptosis. HSP105 may thus be a novel target molecule for cancer therapy and a treatment regimen using synthetic siRNA to suppress the expression of HSP105 protein may provide a new strategy for cancer therapy.

Animals↗

PubMed2006

Elevated plasma osteopontin levels were associated with osteopontin expression of CD4+ T cells in patients with unstable angina.

BACKGROUND: Plaque instability in patients with unstable angina (UA) is associated with stimulated CD4+ T cells, so the present study investigated whether there is a relationship among plaque instability, osteopontin and CD4+ T cells. METHODS AND RESULTS: Peripheral blood mononuclear cells were collected from 51 consecutive patients with UA, 60 patients with stable angina (SA), and 39 patients with chest pain syndrome (CPS). Osteopontin-producing CD4+ T cells were quantified by flow cytometry. Plasma osteopontin levels (ng/ml) were measured by ELISA and were higher in patients with UA (792.0 +/- 316.7) than in those with SA (626.0 +/- 195.0, p < 0.005) or CPS (594.7 +/- 239.4, p < 0.005). The frequency (%) of osteopontin-producing CD4+ T cells was higher in patients with UA (26.7 +/- 13.3) than in those with SA (19.5 +/- 11.1, p < 0.05) or CPS (16.6 +/- 9.0, p < 0.005). Furthermore, the plasma osteopontin level correlated with the frequency of osteopontin-producing CD4+ T cells (r = 0.327, p = 0.0004), as did the high-sensitivity C-reactive protein level (r = 0.360, p = 0.0002). CONCLUSIONS: The plasma osteopontin levels are elevated in patients with UA, accompanied by an increase in the number of osteopontin-production of circulating CD4+ T cells. Circulating CD4+ T cells may play a role through osteopontin in the pathophysiology of UA.

Aged↗

PubMed2006

[Possibilities of glypican-3-specific immunotherapy for hepatocellular carcinoma].

The patients with hepatitis B or C based liver cirrhosis are at high risk for developing Hepatocellular carcinoma (HCC), and HCC patients treated surgically or by other therapies are also at high risk for recurrence. As a result, the prognosis of HCC remains poor, and new therapies for the prevention of cancer development and recurrence are urgently needed. We previously reported that glypican 3 (GPC3) was over expressed specifically in HCC. In this report, we found the HLA-A2 or HLA-A24 restricted GPC3 epitope peptide, and investigated whether these peptides could induce GPC3 reactive CTLs from the peripheral blood mononuclear cells (PBMCs) of HLA-A2+ or HLA-A24+ HCC patients. We used HLA-A2.1 (HHD) transgenic mice (Tgm) to identify the HLA-A2-restricted GPC3 epitopes. We found that these epitope peptides could induce peptide-reactive CTLs in about 50% of HLA A2+ or HLA-A24+, and GPC3+ HCC patients. Our study raises the possibility that these GPC3 peptides may therefore be applicable to cancer immunotherapy for prevention of cancer development and recurrence of HCC.

Aged↗

PubMed2005

Highly sensitive detection of melanoma at an early stage based on the increased serum secreted protein acidic and rich in cysteine and glypican-3 levels.

PURPOSE: There are no available tumor markers detecting primary melanoma at an early stage. The identification of such serum markers would be of significant benefit for an early diagnosis of melanoma. We recently identified glypican-3 (GPC3) as a novel tumor marker but could diagnose only 40% of melanomas. Thereby, we focused out attention on secreted protein acidic and rich in cysteine (SPARC) overexpressed in melanoma as another candidate for tumor marker. EXPERIMENTAL DESIGN: Secreted SPARC protein was quantified using ELISA in the sera from 109 melanoma patients, five patients with large congenital melanocytic nevus, 61 age-matched healthy donors, and 13 disease-free patients after undergoing a surgical removal. We also quantified GPC3 and 5-S-cysteinyldopa in the same serum samples and compared these markers for their diagnostic value. RESULTS: The serum SPARC concentrations in melanoma patients were greater than those in healthy donors (P = 0.001). When we fixed a cutoff value at the mean concentration plus 2 SD of the healthy donors, the serum SPARC was found to have increased in the sera of 36 of the 109 (33%) melanoma patients, whereas there were three (4.9%) false-positive cases of 61 healthy donors. Surprisingly, 19 of 36 patients showing increased SPARC levels were in stages 0 to II. The serum SPARC level decreased under the cutoff level in 10 of 13 patients after surgical removal. Using SPARC and GPC3 in combination thus enabled us to diagnose 47 of 75 (66.2%) melanoma patients at an early stage (0-II). CONCLUSIONS: SPARC or its combination with GPC3 is thus considered a potentially useful tumor marker, especially for melanoma at an early stage.

Adult↗

PubMed2005

Cancer prevention with semi-allogeneic ES cell-derived dendritic cells.

Dendritic cells (DC) genetically modified to present tumor-associated antigen are a promising means for anti-cancer immunotherapy. By introducing expression vectors into ES cells and subsequently inducing differentiation to DC (ES-DC), we can generate transfectant DC expressing the transgenes. In the future clinical application of this technology, the unavailability of human ES cells genetically identical to the patients will be a problem. However, in most cases, semi-allogeneic ES cells sharing some of HLA alleles with recipients are expected to be available. In the present study, we observed that model tumor antigen (OVA)-expressing mouse ES-DC transferred into semi-allogeneic mice potently primed OVA-reactive CTL and elicited a significant protection against challenge with OVA-expressing tumor. Genetic modification of ES-DC to overexpress SPI-6, the specific inhibitor of granzyme B, further enhanced their capacity to prime antigen-specific CTL in semi-allogeneic recipient mice. These results suggest the potential of ES-DC as a novel means for anti-cancer immunotherapy.

Animals↗

PubMed2005

Autoimmunity against neurofilament protein and its possible association with HLA-DRB1*1502 allele in glaucoma.

Glaucoma is understood as a neurodegenerative disease and intraocular pressure has been regarded as the major risk factors for the optic nerve damages. However, recent studies suggested that several risk factors including autoimmunity are also shown to play important roles in glaucoma. To identify the retinal antigen in glaucoma, we used the serological analysis of recombinant cDNA expression libraries (SEREX) approach and quantified IgG antibodies directed against the identified antigens in an ELISA. We identified neurofilament protein and the prevalence of anti-bovine neurofilament light subunit (NF-L) autoantibodies in glaucomatous patients was significantly higher than in healthy controls and patients with other uveitic and optic nerve diseases (P<0.05). In addition, our immunogenetic analysis showed a possible association between HLA-DRB1*1502 allele and the patients positive for anti-NF-L autoantibodies. It suggests that the HLA class II-linked gene may be involved in development of autoimmunity in patients with glaucoma.

Adult↗

PubMed2005

Direct recognition and lysis of leukemia cells by WT1-specific CD4+ T lymphocytes in an HLA class II-restricted manner.

Wilms tumor gene 1 product (WT1) has been recognized as an attractive target antigen of immunotherapy for various malignancies including leukemia. Because tumor-associated antigen-specific CD4+ T lymphocytes undoubtedly play an important role in the induction of an antitumor immune response, we attempted to generate WT1-specific CD4+ T lymphocytes in vitro and examined their antileukemia functions. A CD4+ T-cell line, designated NIK-1, which proliferated and produced Th1 cytokines specifically in response to stimulation with the WT1-derived peptide, WT1(337-347) LSHLQMHSRKH, in an HLA-DP5-restricted manner was established. NIK-1 exhibited cytotoxicity against HLA-DP5-positive, WT1-expressing leukemia cells but did not lyse HLA-DP5-negative, WT1-expressing leukemia cells or HLA-DP5-positive, WT1-negative cells. NIK-1 did not inhibit colony formation by normal bone marrow cells of HLA-DP5-positive individuals. This is the first report to describe WT1-specific and HLA class II-restricted CD4+ T lymphocytes possessing direct cytotoxic activity against leukemia cells.

Amino Acid Sequence↗

PubMed2005

Coculture of Th cells with interleukin (IL)-7 in the absence of antigenic stimuli induced T-cell anergy reversed by IL-15.

Interleukin-7 (IL-7) is an important survival factor for T cells. We report here for the first time that it has another important role, facilitating T-cell clonal unresponsiveness, or anergy. The anergy was induced by a 20-day coculture of activated-human CD4(+) T-cell clones with IL-7 and irradiated peripheral blood mononuclear cells without antigenic stimuli. T-cell survival, but not T-cell anergy induction, was dependent on direct cell contacts between T cells and irradiated peripheral blood mononuclear cells. The anergic T cells exhibited no or very low expression of IL-7 receptor alpha chain (IL-7Ralpha), IL-2 receptor alpha chain (IL-2Ralpha), and common gamma chain (gammac), and did not express cytotoxic T-lymphocyte-associated protein 4, but expressed IL-15Ralpha. Coculture for 3 to 9 days of anergic T cells with a T-cell-activating cytokine IL-15, but not IL-2, restored the responsiveness of IL-7-induced anergic T cells together with reexpressions of IL-7Ralpha, IL-2Ralpha, and gammac. The anergy induction by IL-7 and restoration of responsiveness by IL-15 suggest novel mechanisms for regulation of helper T-cell responses, induction of peripheral tolerance, and breakdown of T-cell self-tolerance.

Antigens↗

PubMed2005

Prevention of experimental autoimmune encephalomyelitis by transfer of embryonic stem cell-derived dendritic cells expressing myelin oligodendrocyte glycoprotein peptide along with TRAIL or programmed death-1 ligand.

Experimental autoimmune encephalomyelitis (EAE) is caused by activation of myelin Ag-reactive CD4+ T cells. In the current study, we tested a strategy to prevent EAE by pretreatment of mice with genetically modified dendritic cells (DC) presenting myelin oligodendrocyte glycoprotein (MOG) peptide in the context of MHC class II molecules and simultaneously expressing TRAIL or Programmed Death-1 ligand (PD-L1). For genetic modification of DC, we used a recently established method to generate DC from mouse embryonic stem cells (ES cells) in vitro (ES-DC). ES cells were sequentially transfected with an expression vector for TRAIL or PD-L1 and an MHC class II-associated invariant chain-based MOG epitope-presenting vector. Subsequently, double-transfectant ES cell clones were induced to differentiate to ES-DC, which expressed the products of introduced genes. Treatment of mice with either of the double-transfectant ES-DC significantly reduced T cell response to MOG, cell infiltration into spinal cord, and the severity of MOG peptide-induced EAE. In contrast, treatment with ES-DC expressing MOG alone, irrelevant Ag (OVA) plus TRAIL, or OVA plus PD-L1, or coinjection with ES-DC expressing MOG plus ES-DC-expressing TRAIL or PD-L1 had no effect in reducing the disease severity. In contrast, immune response to irrelevant exogenous Ag (keyhole limpet hemocyanin) was not impaired by treatment with any of the genetically modified ES-DC. The double-transfectant ES-DC presenting Ag and simultaneously expressing immune-suppressive molecules may well prove to be an effective therapy for autoimmune diseases without inhibition of the immune response to irrelevant Ag.

Adoptive Transfer↗

PubMed2005

DNA vaccination of HSP105 leads to tumor rejection of colorectal cancer and melanoma in mice through activation of both CD4 T cells and CD8 T cells.

We report that HSP105, identified by serological identification of antigens by recombinant expression cloning (SEREX), is overexpressed in a variety of human cancers, including colorectal, pancreatic, thyroid, esophageal, and breast carcinoma, but is not expressed in normal tissues except for the testis. The amino acid sequences and expression patterns of HSP105 are very similar in humans and mice. In this study, we set up a preclinical study to investigate the usefulness of a DNA vaccine producing mouse HSP105 whole protein for cancer immunotherapy in vivo using BALB/c and C57BL/6 mice, Colon26, a syngeneic endogenously HSP105-expressing colorectal cancer cell line, and B16.F10, a melanoma cell line. The DNA vaccine was used to stimulate HSP105-specific T-cell responses. Fifty percent of mice immunized with the HSP105 DNA vaccine completely suppressed the growth of subcutaneous Colon26 or B16.F10 cells accompanied by massive infiltration of both CD4+ T cells and CD8+ T cells into tumors. In cell transfer or depletion experiments we proved that both CD4+ T cells and CD8+ T cells induced by these vaccines play critical roles in the activation of antitumor immunity. Evidence of autoimmune reactions was not present in surviving mice that had rejected tumor cell challenges. We found that HSP105 was highly immunogenic in mice and that the HSP105 DNA vaccination induced antitumor immunity without causing autoimmunity. Therefore, HSP105 is an ideal tumor antigen that could be useful for immunotherapy or the prevention of various human tumors that overexpress HSP105, including colorectal cancer and melanoma.

Animals↗