Distinct role of antigen-specific T helper type 1 (Th1) and Th2 cells in tumor eradication in vivo

Restoration of Thymic Homeostasis in a Tumor-Bearing Host by in Vivo Administration of Medicinal Herb Tinospora Cordifolia

In vivo administration of alcoholic extract of medicinal plant Tinospora cordifolia (TC) to mice bearing a spontaneous T cell lymphoma designated as Dalton's lymphoma prevented tumor growth-dependent regression of thymus. TC was found to augment proliferation of thymocytes with a concomitant decrease in thymocyte apoptosis. It also resulted in a decrease in the number of Hassal's corpuscles. Restoration of thymus homeostasis was caused by TC-dependent augmentation in production of thymocyte growth promoting cytokines Interleukin-2 and Interferon-gamma from thymocytes. TC was found to downregulate thymocyte apoptosis by modulation of Caspase pathway. TC administration retarded tumor growth and prolonged survival of tumor-bearing mice. The possible mechanisms are discussed.

Effect of Subhypnotic Doses of Dexmedetomidine on Antitumor Immunity in Mice

Dexmedetomidine, a selective alpha2 adrenergic receptor agonist, is a drug often used for sedation. Despite the high prevalence of sedating patients with tumors in intensive care settings, little is known about the effect of sedative drugs on tumor growth. We studied the effect of dexmedetomidine on antitumor immunity in mice. Subhypnotic doses of dexmedetomidine decreased interleukin (IL)-12 production from thioglycollate-induced macrophages. The treatment also decreased the ratio of the helper T lymphocytes subsets, Th1 to Th2 (Th1/Th2), in the spleen. Following subcutaneous inoculation of EL4 T-cell lymphoma cells, dexmedetomidine further decreased the splenic Th1/Th2 ratio and activity of EL4-specific cytotoxic T lymphocytes (CTLs). Finally, treatment with dexmedetomidine accelerated EL4 growth in mice. These data show that treatment of mice with subhypnotic doses of dexmedetomidine down-regulates antitumor immunity, possibly through the decreased production of IL-12 from antigen presenting cells, resulting in a Th2 shift and decreased CTL activity against EL4 in mice.

Delivery of noncarrier naked DNA vaccine into the skin by supersonic flow induces a polarized T helper type 1 immune response to cancer

BACKGROUND

DNA vaccine is a new and powerful approach to generate immunological responses against infectious disease and cancer. The T helper type (Th)1 immune response is usually required for generating effective anti-tumor responses. A microparticulate bombardment system can induce an immune response using very low amounts of DNA. Using nozzle aerodynamics, a low pressure gene gun has been developed to decrease the noise associated with high pressure gene guns. Particles are propelled by supersonic flow through this novel nozzle. To test whether this gun could inoculate a DNA vaccine that stimulates an anti-tumor Th1 immune response, we examined the effect of direct delivery of naked DNA (i.e. without any carrier) on the anti-tumor immune response of mice.

METHODS

The luciferase reporter plasmid DNA was delivered using a low-pressure biolistic device and expressed in C3H/HeN, BALB/c, and C57BL/6 mice.

RESULTS

Plasmid DNA expression was mainly in the epidermis. Noncarrier naked neu DNA vaccine and gold particle-coated neu DNA vaccine (at 1 microg per mouse) had similar anti-tumor effects in C3H mice. However, cytokine profile examination showed the Th1-bias of the response induced by naked DNA vaccine and the Th2-bias of the response induced by coated DNA vaccine.

CONCLUSIONS

A shift in the immune response to favour enhanced tumor rejection can be achieved by skin delivery of naked DNA vaccine.

Oxidation of ovarian epithelial cancer cells by hypochlorous acid enhances immunogenicity and stimulates T cells that recognize autologous primary tumor

PURPOSE

Hypochlorous acid, a product of neutrophil myeloperoxidase, is a powerful enhancer of antigen processing and presentation. In this study, we examine whether ovarian epithelial cells (SK-OV-3) exposed to hypochlorous acid can stimulate T cells from patients with ovarian epithelial cancer that recognize common tumor antigens as well as autologous tumor.

EXPERIMENTAL DESIGN

T cells from human leukocyte antigen (HLA)-A2(+) and HLA-A2(-) patients or healthy controls were stimulated with autologous dendritic cells cocultured with the generic ovarian tumor line SK-OV-3, previously exposed to hypochlorous acid.

RESULTS

Hypochlorous acid-treated SK-OV-3 cells drove expansion of CD8(+) T cells from HLA-A2(+) individuals, which recognized the HLA-A2-restricted tumor antigen epitopes of HER-2/neu (E75 and GP2) and MUC1 (M1.1 and M1.2). Up to 4.1% of the T cells were positive for the HER-2/neu KIFGSLAFL epitope using pentamer staining. Dendritic cells loaded with oxidized SK-OV-3 cells and further matured with CD40 agonistic antibody or monophosphoryl lipid A additionally induced CD4(+) class II-restricted responses. Critically, T cells stimulated with mature oxidized SK-OV-3 (but not a control oxidized melanoma cell line) directly recognized autologous tumor cells isolated from patient ascites.

CONCLUSIONS

Immunization with mature dendritic cells loaded with a generic oxidized tumor cell line stimulates a polyclonal antitumor response that recognizes autologous tumor. These findings suggest a new immunotherapeutic strategy to extend remission in ovarian cancer.

Lymphocyte activation gene-3 fusion protein increases the potency of a granulocyte macrophage colony-stimulating factor-secreting tumor cell immunotherapy

PURPOSE

The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy, which is known to stimulate a potent and long-lasting antigen-specific immune response in combination with lymphocyte activation gene-3 fusion protein (LAG-3Ig), which has been shown to act as an adjuvant for priming T helper type 1 and cytotoxic T-cell responses.

EXPERIMENTAL DESIGN

Survival and immune monitoring studies were done in the B16 melanoma model. GM-CSF-secreting tumor cell immunotherapy was administered as a single s.c. injection and LAG-3Ig was administered s.c. at the immunotherapy site.

RESULTS

The studies reported here show that combining LAG-3Ig with GM-CSF-secreting tumor cell immunotherapy prolonged the survival of tumor-bearing animals compared with animals treated with either therapy alone. Prolonged survival correlated with increased numbers of systemic IFN gamma-secreting CD8+ T cells and a significantly increased infiltration of activated effector CD8+ T cells into the tumor. Moreover, an increase in antigen-specific IgG1 humoral responses was detected in serum of animals injected with the combination therapy compared with animals injected with either therapy alone.

CONCLUSION

LAG-3Ig combined with a GM-CSF-secreting tumor cell immunotherapy stimulated both cellular and humoral antitumor immune responses that correlated with prolonged survival in tumor-bearing animals.

Depressed and anxious mood and T-cell cytokine expressing populations in ovarian cancer patients

The adaptive immune response of ovarian cancer patients has been linked to survival, and is known to be impaired in the tumor microenvironment. Little is known about relationships between biobehavioral factors such as depressed mood and anxiety and the adaptive immune response in ovarian cancer. Thirty-seven patients with epithelial ovarian cancer and 14 patients with benign ovarian neoplasms completed psychosocial questionnaires pre-surgery. Lymphocytes from peripheral blood, tumor, and ascites (fluid around the tumor), were obtained on the day of surgery. Expression of the Type-1 cytokine interferon-gamma (IFN gamma), and the Type-2 cytokine interleukin-4 (IL-4) by T-helper (CD4(+)) and T-cytotoxic (CD8(+)) cells was measured under autologous tumor-stimulated, polyclonally-stimulated, or unstimulated conditions. Links with mood were examined. Among cancer patients, marked elevations in unstimulated and tumor-stimulated Type-2 responses were seen, particularly in ascites and tumor-infiltrating lymphocytes (P values<0.01). With polyclonal stimulation, lymphocytes from all compartments expressed elevated Type-1 cytokines (P values<0.014). Depressed and anxious mood were both associated with significantly lower ratios of polyclonally-stimulated CD4(+) cells producing IFN gamma (TH(1) cells) vs. IL-4 (TH(2) cells) in all compartments (depressed mood: P=0.012; anxiety: P=0.038) and depressed mood was also related to lower ratios of polyclonally-stimulated CD8(+) cells producing IFN gamma (TC(1)) vs. IL-4 (TC(2)) (P=0.035). Although effects of polyclonal stimulation should be generalized with caution to the in vivo immune response, findings suggest that depressed and anxious mood are associated with greater impairment of adaptive immunity in peripheral blood and in the tumor microenvironment among ovarian cancer patients.

Different immune correlates associated with tumor progression and regression: implications for prevention and treatment of cancer

Observations show that humans and animals respond immunologically to most cancers. Why does the immune system then fail to control cancer? We argue from the literature that there is a commonality in the regulation of responses against most murine tumors, and that a major mechanism of escape may be deviation of an effective Th1, cytotoxic T lymphocyte response to a less effective response with a Th2 component. We examined this hypothesis with two well-studied murine tumors. We found, following primary tumor implantation, that resistance correlates with Th1 responses and IgG2a antibody production and progression with mixed Th1/Th2 responses and production of IgG1 and IgG2a antibodies. Resistance is associated with a modulation of the anti-tumor response towards the Th1 pole in both systems. We conclude that the immune responses against these two tumors are in accord with our hypothesis, and argue that this is likely to be true of many human and murine tumors. The correlation of IgG isotype of anti-tumor antibody with the Th1/Th2 nature of the anti-tumor response readily allows one to longitudinally monitor the changing nature of the anti-tumor response. We suggest that such monitoring can guide immunotherapy to maximize the effectiveness of the host's immune response against cancer.

Essential role of Toll-like receptors for dendritic cell and NK1.1(+) cell-dependent activation of type 1 immunity by Lactobacillus pentosus strain S-PT84

Activation of type 1 immunity plays a critical role in host defense mechanisms against infectious disease and tumor. Lactic acid bacteria, existing in the gastrointestinal tract, are one of the powerful tools to induce a type-1-dominant immunity, which may improve Th2-dependent allergic diseases. In the present work, we found that an oral intake of Lactobacillus pentosus strain, S-PT84 into mice significantly enhanced NK activity of spleen cells in vivo. We further revealed that NK1.1 positive NK cells and NKT cells are responsible cells for producing IFN-gamma after stimulation with S-PT84 in vitro. S-PT84 induced IFN-gamma-producing cells through activation of IL-12 production by CD11c(+)DCs in Toll-like receptor (TLR) 2- and/or TLR4-dependent manner. Interestingly, direct interaction between DCs and NK1.1(+) cells was also essential for the IFN-gamma production in response to the S-PT84 stimulation. Therefore, we concluded that S-PT84 effectively promoted type 1 immunity through IL-12 and IFN-gamma which were produced by DCs and NK1.1(+) cells, respectively. Thus, S-PT84 would be a nice immune modulator for improving immunobalance, which plays a pivotal role for controlling allergy, infectious diseases and tumor.

An HLA-DR-degenerate epitope pool detects insulin-like growth factor binding protein 2-specific immunity in patients with cancer

Recent studies have shown the importance of helper CD4 T cells in initiating and sustaining tumor-specific CD8 T-cell immunity. This has paved the way for identifying MHC class II epitopes that could be incorporated into class I-based vaccines. In this study, the goal was to identify an HLA-DR-degenerate epitope pool derived from insulin-like growth factor binding protein 2 (IGFBP-2). IGFBP-2, a regulator of insulin-like growth factor action, is overexpressed in the majority of breast and ovarian cancers. Using algorithms, we predicted 29 HLA-DR1-binding epitopes. Binding assays targeting 15 different HLA-DRs revealed that 10 epitopes were degenerate, binding to at least four different HLA-DR variants. An IFN-gamma enzyme-linked immunosorbent spot assay was used to assess immunity to these 10 epitopes in 48 patients with either breast or ovarian cancer and 18 controls. Elevated T-cell immunity in patients was detected in 4 of the 10 epitopes (IGFBP2.17, IGFBP2.22, IGFBP2.249, and IGFBP2.293). The cumulative T-cell frequency of these four epitopes was elevated in patients relative to controls. All four peptides are naturally processed and presented to CD4 T-cells. The degenerate pool of peptides covers nearly 80% of patients and may be useful for augmenting CD4 T-cell immunity in patients undergoing immunization.

Noncytotoxic functions of NK cells: direct pathogen restriction and assistance to adaptive immunity

Natural killer cells were named after their ability to mediate spontaneous cytotoxicity during innate immune responses. However, it has become clear in recent years that they play an equally important role in restricting infections and assisting the development of adaptive immune responses via their ability to produce cytokines. In humans, a dedicated NK cell subset primarily fulfills these later functions. In this review we discuss the noncytotoxic effector functions of NK cells and how they could be harnessed for immunotherapy and vaccine development.

RANTES-403 polymorphism is associated with reduced risk of gastric cancer in women

BACKGROUND

Men are more susceptible to gastric cancer (GC) than women. However, the genetic factors associated with the sex difference are not well understood. Chemokines have been shown to modulate tumor behavior, and the sex-specific effect of the chemokine polymorphisms on the host susceptibility to several diseases has been reported. We aimed to determine the role of chemokine polymorphisms on host susceptibility to GC, with special interest on their sex-specific effect.

METHODS

A hospital-based case-control study, including 177 patients with GC and 217 age-matched unaffected healthy controls, was performed in three major tertiary care hospitals. Genotyping for regulated upon activation, normal T-cell expressed and secreted (RANTES) -403 A/G and -28 C/G, CC chemokine receptor 5 (CCR5) deletion, and CCR2-V64I was performed using peripheral blood DNA.

RESULTS

The RANTES -403 GA and AA genotypes were independently associated with a 2.3-fold reduced risk of developing GC (OR=0.44, 95% CI 0.22-0.90, P=0.025) compared with GG genotype in women, but not in men. The RANTES -28C/G and CCR2-V64I polymorphisms were not associated with different risk of developing GC. The tumor stage, histological features, and survival rate were not different when stratified by RANTES -403 and -28 and CCR2-V64I genotypes.

CONCLUSIONS

Our data indicate that women who inherit A allele at RANTES -403 may be at reduced risk of GC.

Peptide epitope identification for tumor-reactive CD4 T cells

Because T lymphocytes have the capacity to recognize tumor cells, significant efforts are being devoted towards the development of T cell-based immunotherapy for cancer. Most of this work has centered in the induction of anti-tumor CD8 T cells, which exhibit cytolytic activity towards tumor cells expressing tumor-specific or tumor associated antigens. Unfortunately to this day, T cell-based immunotherapy for cancer remains suboptimal. One of the possible explanations is that these immunotherapies have ignored the role that CD4 T helper lymphocytes play in the generation and persistence of CD8 T cell responses. Thus, we believe that in order to obtain clinical benefits T cell-based immunotherapy must stimulate both CD8 and CD4 tumor-reactive T cell responses. During the past seven years our group has focused on the identification of CD4 T cell epitopes from tumor-associated and tumor-specific antigens that could be used to complement the already identified CD8 T cell epitopes to produce effective vaccination strategies against numerous tumor types. We will describe here the strategy we used that resulted in the identification and characterization of numerous CD4 T cell epitopes that are applicable to developing therapies against hematological malignancies and solid tumors.

Tumor-specific Th17-polarized cells eradicate large established melanoma

CD4+ T cells can differentiate into multiple effector subsets, but the potential roles of these subsets in anti-tumor immunity have not been fully explored. Seeking to study the impact of CD4+ T cell polarization on tumor rejection in a model mimicking human disease, we generated a new MHC class II-restricted, T-cell receptor (TCR) transgenic mouse model in which CD4+ T cells recognize a novel epitope in tyrosinase-related protein 1 (TRP-1), an antigen expressed by normal melanocytes and B16 murine melanoma. Cells could be robustly polarized into Th0, Th1, and Th17 subtypes in vitro, as evidenced by cytokine, chemokine, and adhesion molecule profiles and by surface markers, suggesting the potential for differential effector function in vivo. Contrary to the current view that Th1 cells are most important in tumor rejection, we found that Th17-polarized cells better mediated destruction of advanced B16 melanoma. Their therapeutic effect was critically dependent on interferon-gamma (IFN-gamma) production, whereas depletion of interleukin (IL)-17A and IL-23 had little impact. Taken together, these data indicate that the appropriate in vitro polarization of effector CD4+ T cells is decisive for successful tumor eradication. This principle should be considered in designing clinical trials involving adoptive transfer-based immunotherapy of human malignancies.

Sustained antigen-specific antitumor recall response mediated by gene-modified CD4+ T helper-1 and CD8+ T cells

Given that specific subsets of T helper 1 (Th1) and T helper 2 (Th2) CD4(+) T cells have been shown to play key roles in tumor rejection models, we wanted to assess the contribution of either Th1 or Th2 CD4(+) cell subtypes for redirected T-cell immunotherapy. In this study, we have developed a novel method involving retroviral transduction and in vitro T-cell polarization to generate gene-engineered mouse CD4(+) Th1 and Th2 cells or T helper intermediate (Thi) cells expressing an anti-erbB2-CD28-zeta chimeric receptor. Gene-modified Th1 and Th2 polarized CD4(+) cells were characterized by the preferential secretion of IFN-gamma and interleukin-4, respectively, whereas Thi cells secreted both cytokines following receptor ligation. In adoptive transfer studies using an erbB2(+) lung metastasis model, complete survival of mice was observed when transduced Th1, Th2, or Thi CD4(+) cells were transferred in combination with an equivalent number of transduced CD8(+) T cells. Tumor rejection was consistently associated with transduced T cells at the tumor site and interleukin-2 secretion. However, the surviving mice treated with gene-modified Th1 CD4(+) cells were significantly more resistant to a subsequent challenge with a different erbB2(+) tumor (4T1.2) implanted s.c. This result correlated with both increased expansion of Th1 CD4(+) and CD8(+) T cells in the blood and a greater number of these cells localizing to the tumor site following rechallenge. These data support the use of gene-modified CD4(+) Th1 and CD8(+) T cells for mediating a sustained antitumor response.

Potent CTL induction by a whole cell pertussis vaccine in anti-tumor peptide immunotherapy

Promising yet limited clinical responses have been reported for peptide based immunotherapy against tumors. In order to induce more potent cytolytic CD8 T cell responses, we investigated the use of Bordetella pertussis vaccine as an adjuvant for peptide immunization. A whole cell (Wc) vaccine has been known to induce a Th1 biased immune response while an acellular (Ac) vaccine tends to induce that of the Th2 type. Natural infection by B. pertussis helps to maintain a robust Th1 memory in the host population. To examine the adjuvant activity of the pertussis vaccine, we immunized mice with an ovalbumin peptide as a model tumor antigen, and monitored the development of anti-tumor activities. The addition of either the Ac or the Wc vaccine helped expand the specific CD8 T cells. However, there was a marked difference in the induced cytolytic activity where the Wc vaccine was superior to the Ac. The Wc vaccine was also more effective in inducing in vivo tumor rejection. The adjuvant activity was not only effective against ovalbumin, but was also evident when an endogenous tumor antigen, Wilms' tumor 1 gene product, was targeted. These results indicate that, although the Wc vaccine does not share the same antigen specificity with tumor cells, it can aid in the development of highly cytolytic CD8 T cells as an adjuvant at the site of peptide immunization.

Th2-mediated anti-tumour immunity: friend or foe?

The concept that the immune system can recognise tumour cells and either eliminate them (tumour immune surveillance) or select for immunologically resistant variants (immunoediting) is gaining general acceptance by immunologists. In terms of an adaptive immune response to cancer, however, much of the research has focused on the response of cytotoxic CD8+ T lymphocytes to tumour-specific antigens and the production of Th1 cytokines by CD4+ and CD8+ T cells. In contrast, Th2-mediated immunity has traditionally been viewed as favouring tumour growth, both by promoting angiogenesis and by inhibiting cell-mediated immunity and subsequent tumour cell killing. While there is evidence that components of type 2 inflammation, such as B cells and interleukin-10, do promote tumour growth, there are also many studies demonstrating the anti-tumour activity of CD4+ Th2 cells, particularly in collaboration with tumour-infiltrating granulocytes, such as eosinophils. In this review, we examine all the components of type 2 immunity and their effects on tumour growth. Collectively, from this analysis, we conclude that there is a great potential for the development of Th2-mediated immunotherapies that harness the cytotoxic activity of eosinophils.

Long-lasting balanced immunity and protective efficacy against respiratory syncytial virus in mice induced by a recombinant protein G1F/M2

Respiratory syncytial virus (RSV) is the primary cause of serious lower respiratory tract illness in young children. We have engineered a recombinant candidate vaccine G1F/M2, consisting of a cytotoxic T lymphocyte (CTL) epitope of RSV-M2 protein and a domain of RSV-G protein. In this study, the long-term immunogenicity and protective effect were evaluated. In G1F/M2-immunized mice, special antibodies lasted for more than 19 weeks, and the IgG1/IgG2a ratio remained a balanced level till the end of the study, suggesting mixed Th1/Th2 type of responses. Concomitantly, G1F/M2 elicited long-lived RSV-specific CTL activity that was detectable at 12 weeks after the final immunization. Stronger CTL responses were induced with immunization once more at 13 weeks after the last immunization in G1F/M2-primed mice than those in F/M2-primed mice. These results suggest that G1F/M2-induced long-lasting balanced humoral and cellular immunity responses, and immunological memory in mice. Furthermore, following RSV challenge, long-term protective efficacy was observed. RSV replication in lungs of G1F/M2-primed mice elicited also mixed Th1/Th2 responses, a property that is considered advantageous for the safety of an RSV vaccine. Therefore, G1F/M2 is a promising RSV subunit vaccine.

Recombined CC chemokine ligand 2 into B16 cells induces production of Th2-dominant [correction of dominanted] cytokines and inhibits melanoma metastasis

This study is aimed to verify whether CCL2 can induce Th2 polarization in vivo and subsequently inhibit tumor metastasis. B16 cells (a murine melanoma cell line) highly expressing CCL2 (CCL2-B16 cells) were obtained by transfection with recombinant plasmid CCL2-pcDNA3. Primary thymocytes were co-cultured with CCL2-B16 cells and STAT-6-mediated Th2 polarization was noticed after co-culture. Caudal vein injection of CCL2-B16 cells effectively inhibited pulmonary metastasis in C57BL/6 mice, but not in nude mice, indicating that T cells play a role in CCL2-induced inhibition of tumor metastasis. We found that high level of CCL2 up-regulated the expression of Th2-related cytokine (IL-4) in tumor microenvironment and increased CD4+, CD8+, and CD45RB+ cells in the peripheral blood and tumor tissues. We also demonstrated that inoculation of mice with CCL2-B16 cells prolonged mice survival time when they were reinjected with wildtype B16 cells, implying that CCL2 can activate immuno-memory in mice. It is concluded that high expression of CCL2 can induce Th2 polarization in tumor microenvironment and can effectively inhibit tumor metastasis, which casts new lights on the role of chemokines in reconstruction of immune surveillance in patients suffering from tumors.

Preferential expression of very late antigen-4 on type 1 CTL cells plays a critical role in trafficking into central nervous system tumors

We have previously shown preferential tumor-homing and therapeutic efficacy of adoptively transferred type 1 CTL (Tc1) when compared with type 2 CTL (Tc2) in mice bearing intracranial ovalbumin-transfected melanoma (M05). Further characterizing the expression of a panel of homing receptors on Tc1 and Tc2 cells, we found that very late antigen (VLA)-4 (a heterodimer of CD49d and CD29), but none of other receptors evaluated, was expressed at significantly higher levels on Tc1 cells than on Tc2 cells. Although CD49d (alpha(4) integrin) can form heterodimers with both beta(1) (CD29) and beta(7) integrins, alpha(4)beta(7) complexes were not expressed by either Tc1 or Tc2 cells, suggesting that CD49d is solely expressed in VLA-4 complexes. VLA-4 expression on Tc2 cells was down-regulated in an interleukin (IL)-4 dose-dependent manner but not by other type 2 cytokines, such as IL-10 and IL-13, suggesting that IL-4 uniquely down-regulates VLA-4 expression on these cells. In accordance with the differential expression of VLA-4 on Tc1 versus Tc2 cells, Tc1 cells alone were competent to adhere to plate-bound VCAM-1-Ig fusion protein. Finally, the efficient trafficking of Tc1 cells into intracranial M05 lesions in vivo was efficiently blocked by administration of monoclonal antibodies against CD49d or VCAM-1 or small interfering RNA-mediated silencing of CD49d on Tc1 cells. Collectively, these data support the critical role of VLA-4 in the effective intracranial tumor homing of adoptive-transferred, antigen-specific Tc1 cells and suggest that more effective vaccine and/or ex vivo T-cell activation regimens may be developed by promoting the generation of VLA-4(+) antitumor Tc1 cells.

Recognition of prostate and melanoma tumor cells by six-transmembrane epithelial antigen of prostate-specific helper T lymphocytes in a human leukocyte antigen class II-restricted manner

The six-transmembrane epithelial antigen of prostate (STEAP) protein is an attractive candidate for T cell-based immunotherapy because it is overexpressed in prostate cancer and various other tumor types. Several peptide epitopes capable of stimulating CTLs that killed STEAP-expressing tumor cells have been described. Our goal was the identification of helper T lymphocyte (HTL) epitopes of STEAP for the optimization of T cell-based immunotherapies against STEAP-expressing malignancies. Candidate HTL epitopes for STEAP were predicted using in silico algorithms for HLA class II-binding peptides and were tested for their ability to elicit HTL responses by in vitro peptide vaccination of CD4 T lymphocytes from healthy individuals and prostate cancer patients. Two peptides (STEAP(102-116) and STEAP(192-206)) were effective in stimulating in vitro antitumor HTL responses in both normal individuals and prostate cancer patients. Notably, both STEAP HTL peptides behaved as promiscuous T-cell epitopes because they stimulated T cells in the context of more than one MHC class II allele. These newly described STEAP HTL epitopes could be of value for the design and optimization of T cell-based immunotherapy against STEAP-expressing tumors.

Combination tumor immunotherapy with radiotherapy and Th1 cell therapy against murine lung carcinoma

Mice bearing established Lewis lung carcinoma (LLC) expressing model tumor antigen, ovalbumin (OVA) (LLC-OVA) marginally responded to local radiotherapy, but none of the mice was cured. In contrast, treatment of the tumor-bearing mice with intratumoral injection of tumor-specific T helper type 1 (Th1) cells and tumor antigen (OVA) after radiotherapy dramatically prolonged the survival days and induced complete cure of the mice at high frequency (80%). Radiation therapy combined with Th1 cells or OVA alone showed no significant therapeutic activity against LLC-OVA. Such a strong therapeutic activity was not induced by intratumoral injection of Th1 cells plus OVA. Compared with other treatment, radiation therapy combined with Th1 cells and OVA was superior to induce the generation of OVA/H-2(b) tetramer(+) tumor-specific cytotoxic T lymphocyte (CTL) with a strong cytotoxicity against LLC-OVA in draining lymph node (DLN). Moreover, the combined therapy is demonstrated to inhibit the growth of tumor mass, which grew at contralateral side. These results indicated that radiotherapy combined with Th1 cell/vaccine therapy induced a systemic antitumor immunity. These findings suggested that combination therapy with radiotherapy and Th1 cell/vaccine therapy may become a practical strategy for cancer treatment.

Identification of a novel NY-ESO-1 promiscuous helper epitope presented by multiple MHC class II molecules found frequently in the Japanese population

NY-ESO-1 is a cancer-testis antigen that elicits strong cellular and humoral immune responses against NY-ESO-1-expressing tumors. Although CD4(+) T cells play a critical role in inducing antitumor immunity, little is known about MHC class II-restricted helper epitopes of the NY-ESO-1 antigen compared with MHC class I-restricted epitopes. Here, we searched for new NY-ESO-1 helper epitopes presented by MHC class II molecules, especially those found frequently in the Japanese population. We established five NY-ESO-1-specific helper T-cell lines from healthy Japanese donors using NY-ESO-1 recombinant protein and peptide. Using MHC class II-specific antibodies and a panel of Epstein-Barr virus-transformed B-cell lines, it was demonstrated that four out of the five T-cell lines recognized a region within NY-ESO-1(119-143) in the context of HLA-DRB1*0802, DRB1*0901, DRB1*1502 or DRB1*0405/*0410. In addition, using a set of overlapping 15-mer synthetic peptides, we found that NY-ESO-1(122-138) was a promiscuous region that bound to four distinct HLA-DR molecules found in the Japanese population. These findings expand the usefulness of NY-ESO-1 as a tool for tumor vaccine therapy in eliciting NY-ESO-1-specific helper T-cell responses, especially in Japanese cancer patients.

Enhancement of IFN-gamma production for Th1-cell therapy using negatively charged liposomes containing phosphatidylserine

We have developed an efficient method of interferon-gamma (IFN-gamma) induction for Th1-cell therapy. OVA (ovalbumin)-specific Th1 clone 42-6A cells cocultured with antigen presenting cells (APCs) from spleen resulted in high levels of OVA-specific IFN-gamma production by the treatment of phosphatidylserine (PS), but not phosphatidic acid (PA), liposomes-encapsulated OVA (OVA-liposomes). The IFN-gamma production was increased in a manner dependent on the PS content of the liposomes and inhibited by the addition of annexin V, a PS binding protein. Furthermore, coadministration of Th1 cells plus OVA-liposomes in mice strikingly enhanced IFN-gamma levels in serum and in spleen cells compared with that of Th1 cells plus OVA. In addition, serum levels of IL-12 p70 increased and ongoing OVA-specific IgE immune response was dramatically attenuated. These results first suggest that antigen delivery using negatively charged liposomes containing PS is very useful for the enhancement of IFN-gamma production in Th1-cell therapy.

Lymphomas can develop from B cells chronically helped by idiotype-specific T cells

B cell lymphomas have been associated with chronic infections and autoimmunity. However, most lymphomas develop in the absence of any known chronic antigenic stimulation. B cells process their highly diversified endogenous immunoglobulin and present clonally unique variable-region idiotypic (Id) peptides on their major histocompatibility complex (MHC) class II molecules to Id-specific T cells. We show that B cells chronically helped by Id-specific Th2 cells developed into large B cell lymphomas with cytogenetic DNA aberrations. The lymphomas expressed high amounts of Id, MHC class II, CD80/86, and CD40 and bidirectionally collaborated with Th2 cells. Thus, MHC class II–presented Id peptides may represent a chronic self-antigenic stimulus for T cell–dependent lymphomagenesis. Eventually, B lymphomas grew independent of T cells. Thus, T cells do not only eliminate cancers as currently believed. In fact, Id-specific Th2 cells can induce B lymphomas.

Early detection and rapid isolation of leukemia-reactive donor T cells for adoptive transfer using the IFN-gamma secretion assay

PURPOSE

The poor immunogenicity of most leukemias and the lack of specificity of the donor T cells limit the in vivo effectiveness of conventional donor lymphocyte infusions in many patients suffering from persistent or recurrent leukemia after allogeneic stem cell transplantation. These limitations may be overcome by the adoptive transfer of in vitro generated leukemia-reactive T cells. Although the potential clinical efficacy of this approach has been shown previously, lack of reproducibility of the procedure and the inability to show persistence and survival of the transferred T cells hampered further clinical application. The purpose of this study was to develop a new, broadly applicable strategy for the efficient generation and isolation of leukemia-reactive T cells with a better probability to survive and expand in vivo.

EXPERIMENTAL DESIGN

Myeloid and B-cell leukemias were modified into professional immunogenic antigen-presenting cells, and used to stimulate HLA-matched donor T cells. After two stimulations, responding donor T cells were isolated based on their secretion of IFN-gamma and tested for their capacity to recognize and kill the primary leukemia.

RESULTS

Using one universal stimulation and isolation protocol for various forms of leukemia, T-cell populations containing high frequencies of leukemia-reactive T cells could reproducibly be generated and early isolated under mild stimulatory conditions. Isolated T cells still had high proliferative potential and their reactivity seemed to be restricted to cells of the patient's hematopoiesis.

CONCLUSION

We here show a new robust procedure for the generation and isolation of leukemia-reactive T cells for adoptive transfer.

Response of lymphocyte subsets and cytokines to Shenyang prescription in Sprague-Dawley rats with tongue squamous cell carcinomas induced by 4NQO

Background

The study was designed to investigate immunocompetence in relation to cancer progression in rat and to assess the effect of the traditional Chinese anti-cancer medicine, "Shenyang" prescription, on immunity.

Methods

4-Nitroquinoline-1-oxide (4NQO) was administered to 80 Sprague-Dawley (SD) rats via the drinking water for up to 36 weeks. Tongue squamous cell carcinoma (SCC) was confirmed by pathological examination in 61 rats. "Shenyang" prescription was administered to subgroups of these rats, and blood samples were taken before and after treatment. Lymphocyte subsets were determined by flow cytometry. Serum Th1 and Th2-type cytokines were assessed by an enzyme-linked immunosorbent assay.

Results

As the cancer progressed at the tongue root, the percentage of CD3+CD4+ T lymphocytes and NK cells and the levels of IFN-γ and IL-2 decreased gradually, while the percentage of CD3+CD8+ T lymphocytes and the levels of IL-4 and IL-10 increased. The CD4+/CD8+ ratios were lower in the cancer groups than in the control group. However, after administering "Shenyang" prescription, the levels of CD3+CD4+ T lymphocytes, NK cells, IFN-γ and IL-2 increased, while the CD3+CD8+ T lymphocyte counts and the levels of IL-4 and IL-10 decreased.

Conclusion

4NQO-induced lesions were good models for exploring oral cavity carcinogenesis. The rats with 4NQO-induced SCC demonstrated abnormalities in lymphocyte subsets and a shift from Th1-type to Th2-type, which were good models for assessing the effect of anticancer agent on immunity. Oral cancer progression was associated with an aggressive disturbance of immune function. "Shenyang" prescription has the ability to improve the disturbance of immune function.

alpha-fetoprotein and interleukin-18 gene-modified dendritic cells effectively stimulate specific type-1 CD4- and CD8-mediated T-Cell response from hepatocellular carcinoma patients in Vitro

The T-helper 1 (Th1) immune reaction is most important in dendritic cell (DC)-based immunotherapy. Interleukin (IL)-18, a Th1-biasing cytokine, plays a pivotal role in inducing cytotoxic T lymphocyte (CTL) responses. In this study, we analyzed whether dendritic cells (DCs) from patients with hepatocellular carcinoma (HCC) can be transduced with the IL-18 gene and/or alpha-fetoprotein (AFP) gene, and we examined whether vaccinations using these genetically engineered DC can induce stronger therapeutic antitumor immunity. The results showed that DC transfected with AdIL-18/AFP can expressed IL-18 and AFP by reverse transcriptase-polymerase chain reaction and enzyme-linked immunoassay. Compared with those before transfection, the expressions of membrane molecules were increased dramatically. Specific T cells generated by DC transfected with AdIL-18/AFP recognized HLA-matched HepG2 cell lines specifically. Most importantly, The cytotoxic activity of CTLs against HepG2 with DC expressing AFP(AFP-DC) was significantly augmented by co-transduction with the IL-18 gene. Administration with such vaccine also significantly increased the production of interleukin-12p70 and interferon-gamma. These results indicate that a vaccination therapy using DC co-transduced with the TAA gene and IL-18 genes is effective strategy for immunotherapy in terms of the activation of DCs, CD4+ T, cells and CD8+ T cells, and may be useful in the clinical application of a cancer vaccine therapy.

The role of CD4+ T cell help in cancer immunity and the formulation of novel cancer vaccines

Recent years have seen the unprecedented surge of interest in the role of CD4+ T cells and the role they play in the development of the immune response. In this symposium review, we examine the evidence for this and discuss their functions, particularly in respect to the cancer immunology, including CD4+CD25+ cells (Treg).

Effects of low-dose irradiation on enhancement of immunity by dendritic cells

Low-doses of irradiation have been reported to have beneficial effects, particularly anti-tumor effects. In this paper, we show the effects of the low-dose irradiation on T cell activation induced by dendritic cells (DCs). DCs, which had been pre-irradiated at 0.02-1.0 Gy from a (137)Cs source, were cultured with allogeneic T cells, and the proliferation of T cells was then examined. The 0.05Gy-pre-irradiated DCs showed the highest proliferation capacity of T cells. The 0.05Gy-irradiation does not augment the expression of major histocompatibility complexes (MHCs) or costimulatory molecules on DCs, as with non-irradiated DCs or 1Gy-irradiated DCs, but does augment the production of IL-2, IL-12 and IFN-gamma DCs. These results suggest that the low-dose irradiation augments T cell-activation capacity through cytokine production by DCs, which might shift naïve helper T cells to Th1 cells.

Induction of potent anti-tumor immunity by direct injection of Ad-LIGHT at the site of tumor inoculation

BACKGROUND

The aim of this study was to observe the therapeutic effects of adenovirus-mediated LIGHT gene transfer in murine B16 melanoma in vivo.

METHODS

C57BL/6 mice were inoculated subcutaneously with B16 cells to establish the murine melanoma model. The tumor-bearing mice were injected at the site of tumor inoculation with recombinant adenoviral vectors expressing the murine LIGHT gene. The tumor growth and survival period of tumor-bearing mice were observed. The splenic NK and CTL activity were measured in vitro by lactate dehydrogenase (LDH) release assay. The amounts of cytokines were determined with ELISA kits.

RESULTS

The LIGHT gene could be efficiently transduced into tumor tissue after injection of Ad-LIGHT. Treatment with Ad-LIGHT significantly inhibited the tumor growth and prolonged the survival period of the tumor-bearing mice. The splenic NK and CTL activity of the mice was also enhanced after LIGHT gene transfer. The production of IL-2 and IFN-gamma from lymphocytes derived from mice treated with Ad-LIGHT was increased significantly compared with control groups.

DISCUSSION

Our results indicate that local expression of the LIGHT gene can induce potent anti-tumor immunity and may be a promising treatment strategy for melanoma.

NK cells of human secondary lymphoid tissues enhance T cell polarization via IFN-gamma secretion

Human secondary lymphoid tissues harbor NK cells that predominantly secrete cytokines in response to activation. Here, we demonstrate that these immunoregulatory NK cells assist in the Th1 polarization of primary immune responses, induced by dendritic cells. Tonsilar, but not peripheral blood NK cells enhanced the expansion of IFN-gamma-producing CD4+ T cells via their superior ability to produce IFN-gamma. Addition of IFN-gamma increased Th1 polarization while antibody blocking of this cytokine abolished NK cell-dependent Th1 polarization. Our data suggest that NK cells in secondary lymphoid organs assist priming of Th1 cells via cytokine secretion and this effect should be harnessed during vaccination against viruses and tumors.

CD8+ cytotoxic T-APC stimulate central memory CD8+ T cell responses via acquired peptide-MHC class I complexes and CD80 costimulation, and IL-2 secretion

We previously showed that naive CD4+ Th cells acquire peptide-MHC class I (pMHC I) and costimulatory molecules from OVA-pulsed dendritic cells (DC(OVA)), and act as Th-APCs in stimulation of CD8+ CTL responses. In this study, we further demonstrated that naive CD8+ cytotoxic T (Tc) cells also acquire pMHC I and costimulatory CD54 and CD80 molecules by DC(OVA) stimulation, and act as Tc-APC. These Tc-APC can play both negative and positive modulations in antitumor immune responses by eliminating DC(OVA) and neighboring Tc-APC, and stimulating OVA-specific CD8+ central memory T responses and antitumor immunity. Interestingly, the stimulatory effect of Tc-APC is mediated via its IL-2 secretion and acquired CD80 costimulation, and is specifically targeted to OVA-specific CD8+ T cells in vivo via its acquired pMHC I complexes. These principles could be applied to not only antitumor immunity, but also other immune disorders (e.g., autoimmunity).

Transduction of an HLA-DP4-restricted NY-ESO-1-specific TCR into primary human CD4+ lymphocytes

cDNAs encoding functional T cell receptor (TCR) alpha and beta chains from a CD4+ T cell line (SG6) generated by repeated stimulation of a melanoma patient's peripheral blood mononuclear cells with HLA-DP4-restricted, NY-ESO-1-specific peptide p161-180 were cloned using a 5'rapid amplification of cDNA end method. Three different TCR alpha chains and 7 TCR beta chains were found among the 84 alpha and 162 beta cDNA clones tested. By screening different combination of the alpha/beta chains using RNA electroporation, TRAV9-1 (Valpha22.1) and TRBV20-1 (Vbeta2) were found to be the functional pair in line SG6. Antibody blocking experiments confirmed that the specificity of TRAV9-1/TRBV20-1 mRNA-transfected T cells were CD4 dependent and HLA-DP4 restricted. A retroviral vector expressing both TRAV9-1 and TRBV20-1 was constructed and used for transduction of OKT3-stimulated peripheral blood lymphocytes from melanoma patients. TCR-transduced CD4 T cells were capable of recognizing peptide-pulsed antigen-presenting cells (Epstein-Barr virus transformed B-cells, dendritic cells, and peripheral blood mononuclear cells), and protein-pulsed dendritic cells. Transduced cells were also capable of proliferation upon peptide stimulation and recognized peptide concentrations that were recognized by the parental line (0.2 microM). In contrast to SG6, which could not recognize human tumors, TCR-transduced CD4 T cells could specifically recognize NY-ESO-1/HLA-DP4-expressing melanoma cells. Major histocompatibility complex class II TCR-transduced CD4 T cells provides an alternative source of tumor antigen-specific T cells for adoptive immunotherapy of cancer patients.

Antitumor activity of chimeric immunoreceptor gene-modified Tc1 and Th1 cells against autologous carcinoembryonic antigen-expressing colon cancer cells

To generate tumor-specific and interferon (IFN)-gamma-producing Tc1 and Th1 cells applicable for many cancer patients, we previously developed a protocol for generating carcinoembryonic antigen (CEA)-specific Tc1 and Th1 cells from healthy human T cells by transduction with a lentivirus containing a chimeric immunoglobulin T-cell receptor (cIgTCR) gene composed of single-chain variable fragments from an anti-CEA-specific monoclonal antibody fused to an intracellular signaling domain of CD28 and CD3zeta. These cells, designated Tc1-T and Th1-T bodies, respectively, showed strong antitumor activity against CEA-expressing tumor cells in RAG2-/- mice when both of them were transferred. However, it remains unclear whether it is possible to generate Tc1-T and Th1-T bodies from cancer patients with defective T-cell function because of significant immunosuppression. Here, we prepared Tc1-T and Th1-T bodies from T cells of a colon cancer patient, and asked whether these T bodies can exert effective T-cell function against autologous tumor cells. These T bodies showed high cytotoxicity and produced IFN-gamma in response to CEA-expressing autologous tumor cells, even in the presence of soluble CEA. It was also demonstrated that Th1-T bodies supported the survival of Tc1-T bodies through cell-to-cell interactions. Furthermore, our protocol utilized retrovirus for cIgTCR transduction to achieve better induction efficiency compared to lentivirus-mediated transduction. Taken together, our findings here indicate that retrovirally transduced Tc1-T and Th1-T bodies will become a promising strategy for adoptive immunotherapy of human cancer.

CD8 alpha coreceptor to improve TCR gene transfer to treat melanoma: down-regulation of tumor-specific production of IL-4, IL-5, and IL-10

Therapeutic success of TCR gene transfer to treat tumors depends on the ability of redirected T cells to become activated upon tumor recognition in vivo. Help provided by tumor-specific Th1 cells is reported to relieve T cells from an anergized state and to induce tumor regression. We recently demonstrated the ability to generate melanoma-specific Th1 cells by genetic introduction of both a CD8-dependent TCR and the CD8alpha coreceptor into CD4+ T cells. In this study, we analyzed a TCR that binds Ag independently of CD8, a property generally preferred to induce tumor-specific T cell responses, and addressed the contribution of CD8alpha following introduction into TCR-transduced CD4+ T cells. To this end, primary human CD4+ T cells were gene transferred with a high-avidity TCR, and were shown not only to bind peptide/MHC class I, but also to effectively kill Ag-positive tumor cells in the absence of CD8alpha. The introduction of CD8alpha up-regulates the tumor-specific production of TNF-alpha and IL-2 to some extent, but significantly down-regulates production of IL-4, IL-5, and IL-10 in CD4+ T cells. The introduction of a mutated cysteine motif in CD8alpha, which prevents its binding to LCK and linker for activation of T cells, did not adversely affect expression and T cell cytotoxicity, but counteracted the CD8alpha-mediated down-regulation of IL-4 and IL-5, but not IL-10. In conclusion, CD8alpha down-regulates the production of major Th2-type cytokines, in part mediated by LCK and/or linker for activation of T cells, and may induce differentiation of tumor-specific Th1 cells, which makes this coreceptor an interesting candidate to improve the clinical potential of TCR gene transfer to treat cancer.

Polyarginine-Mediated Protein Delivery to Dendritic Cells Presents Antigen More Efficiently onto MHC Class I and Class II and Elicits Superior Antitumor Immunity

Protein transduction domains (PTDs) have been used increasingly to deliver reagents to a variety of cell types in vitro and in vivo. We have previously shown that HIV TAT-PTD-containing whole protein antigens (Ags)-transduced dendritic cells (DCs) stimulated Ag-specific CD8+ and CD4+ T cells. Although the cytotoxic T lymphocytes (CTL) activity generated was sufficient to prevent engraftment of mice with Ag-expressing tumors, treatment of tumor-bearing mice with TAT-PTD Ag-transduced DCs resulted in tumor regression in some animals. Recently, several other PTDs were reported to promote higher transduction efficiencies than TAT-PTD. To evaluate the role of individual PTDs in induction of immune responses in tumor vaccination studies, we engineered recombinant fusion Ovalbumin (OVA) that contained three differrent PTDs, including the most efficacious known PTD (polyarginine (R9)-PTD). Our results demonstrated that R9-PTD-containing OVA transduced DCs most efficiently, and that transduction efficacy was closely correlated with the extent of Ag-specific CD4+ and CD8+ T-cell activation in vitro and in vivo. Repeated vaccination with R9-PTD-OVA-transduced DC in (OVA-expressing) tumor-bearing mice induced enhanced antitumor immunity, and elicited complete rejection of tumors when DC was co-injected with adjuvants. This vaccination strategy may be clinically applicable, and offers theoretical and practical advantages to those that are in current use.

Immunization with autologous T cells enhances in vivo anti-tumor immune responses accompanied by up-regulation of GADD45β

Immunization with inactivated autoreactive T cells may induce idiotype anti-idiotypic reactions to deplete autoreactive T cells, which are involved in autoimmune diseases. However, it is unknown whether attenuated activated healthy autologous T-cell immunization could increase anti-tumor immune responses. To this end, C57Bl/6 mice were immunized with attenuated activated autologous T cells. The splenocytes from immunized mice showed a higher proliferative ability than that from naive mice. The special phenotype analysis showed that there were more CD8+ T cells and CD62L+ T cells in immunized mice after 24 h of culture with 10% fetal calf serum complete medium in vitro (P<0.01). These results demonstrated that this immunization may activate T cells in vivo. Furthermore, the splenocytes from immunized mice revealed resistance to activation-induced cell death (AICD) in vitro. To further study the relative genes that are responsible for the higher proliferation and resistance to AICD, the expression of Fas/Fas ligand (FasL) and GADD45b was measured by real-time PCR. The results indicated that GADD45beta transcription was higher in the splenocytes from immunized mice than that in the naive mice. In addition, the Fas expression showed a parallel higher, but FasL did not change obviously. To investigate the biologic functions induced by immunization in vivo, a tumor model was established by EL-4 tumor cell inoculation in C57/Bl mice. Mice receiving autologous T-cell immunization had significantly inhibited tumor growth in vivo (P<0.01). This study implicated that immunization with attenuated activated autologous T cells enhances anti-tumor immune responses that participate in tumor growth inhibition.

Defining MHC class II T helper epitopes for WT1 tumor antigen

The product of Wilms' tumor gene 1 (WT1) is overexpressed in diverse human tumors, including leukemia, lung and breast cancer, and is often recognized by antibodies in the sera of patients with leukemia. Since WT1 encodes MHC class I-restricted peptides recognized by cytotoxic T lymphocytes (CTL), WT1 has been considered as a promising tumor-associated antigen (TAA) for developing anticancer immunotherapy. In order to carry out an effective peptide-based cancer immunotherapy, MHC class II-restricted epitope peptides that elicit anti-tumor CD4(+) helper T lymphocytes (HTL) will be needed. In this study, we analyzed HTL responses against WT1 antigen using HTL lines elicited by in vitro immunization of human lymphocytes with synthetic peptides predicted to serve as HTL epitopes derived from the sequence of WT1. Two peptides, WT1(124-138) and WT1(247-261), were shown to induce peptide-specific HTL, which were restricted by frequently expressed HLA class II alleles. Here, we also demonstrate that both peptides-reactive HTL lines were capable of recognizing naturally processed antigens presented by dendritic cells pulsed with tumor lysates or directly by WT1+ tumor cells that express MHC class II molecules. Interestingly, the two WT1 HTL epitopes described here are closely situated to known MHC class I-restricted CTL epitopes, raising the possibility of stimulating CTL and HTL responses using a relatively small synthetic peptide vaccine. Because HTL responses to TAA are known to be important for promoting long-lasting anti-tumor CTL responses, the newly described WT1 T-helper epitopes could provide a useful tool for designing powerful vaccines against WT1-expressing tumors.

Soluble human LAG-3 molecule amplifies the in vitro generation of type 1 tumor-specific immunity

The adjuvant activities of the human lymphocyte activation gene-3 (LAG-3) molecule have been evaluated in a human setting by investigating the ability of a soluble recombinant human LAG-3 protein (hLAG-3Ig) to enhance the in vitro induction of viral- and tumor-specific CTLs. We found that soluble human LAG-3 significantly sustained the generation and expansion of influenza matrix protein Melan-A/MART-1 and survivin-specific CD8+ T lymphocytes in peripheral blood mononuclear cells (PBMC) of both cancer patients and healthy donors, showing its ability to boost CD8+ T-cell memory response or to prime naive T cells in vitro. The peptide-specific T cells generated in the presence of hLAG-3Ig were endowed with cytotoxic activity and enhanced release of type 1 cytotoxic T (Tc1) cytokines and were able to recognize tumor cells expressing their nominal antigen. Phenotype and cytokine/chemokines produced by antigen-presenting cells (APC) of PBMCs exposed in vitro for 2 days to peptide and hLAG-3Ig indicate that the LAG-3-mediated adjuvant effect may depend on a direct activation of circulating APCs. Our data revealed the activity of hLAG-3Ig in inducing tumor-associated, antigen-specific CD8+ T-cell responses in a human setting and strongly support the conclusion that this recombinant protein is a potential candidate adjuvant for cancer vaccines.

An overview of the association between allergy and cancer

Numerous epidemiological studies have evaluated some aspect of the association between a history of allergy and cancer occurrence. In this article, an overview of the epidemiological evidence is presented with a discussion of a number of methodological issues important in this area of study. Literature searches were conducted using the MEDLINE database from 1966 through to August 2005 to identify articles that explored a personal history of allergic disorders as a risk factor for cancer. Although it is difficult to draw conclusions between allergy and cancer at many sites because of insufficient evidence or a lack of consistency both within and among studies completed to date, strong inverse associations have been reported for pancreatic cancer and glioma, whereas lung cancer was positively associated with asthma. Additional studies are needed to confirm these finding and to address the limitations of previous studies, including the validity and reliability of exposure measures and control for confounding. Further, large prospective studies using cancer incidence would be particularly useful, including studies using biological markers of allergic status to reduce potential misclassification and to confirm the results of previous studies based on self-report. There is also a need for further basic research to clarify a potential mechanism, should an association exist.

Alphabeta T-cell receptor engineered gammadelta T cells mediate effective antileukemic reactivity

Retroviral transfer of T-cell receptors (TCR) to peripheral blood-derived T cells generates large numbers of T cells with the same antigen specificity, potentially useful for adoptive immunotherapy. One drawback of this procedure is the formation of mixed TCR dimers with unknown specificities due to pairing of endogenous and introduced TCR chains. We investigated whether gammadelta T cells can be an alternative effector population for TCR gene transfer because the gammadeltaTCR is not able to form dimers with the alphabetaTCR. Peripheral blood-derived gammadelta T cells were transduced with human leukocyte antigen (HLA) class I- or HLA class II-restricted minor histocompatibility antigen (mHag) or virus-specific TCRs. Because most gammadelta T cells do not express CD4 and CD8, we subsequently transferred these coreceptors. The TCR-transduced gammadelta T cells exerted high levels of antigen-specific cytotoxicity and produced IFN-gamma and IL-4, particularly in the presence of the relevant coreceptor. gammadelta T cells transferred with a TCR specific for the hematopoiesis-specific mHag HA-2 in combination with CD8 displayed high antileukemic reactivity against HA-2-expressing leukemic cells. These data show that transfer of alphabetaTCRs to gammadelta T cells generated potent effector cells for immunotherapy of leukemia, without the expression of potentially hazardous mixed TCR dimers.

Identification of oncofetal antigen/immature laminin receptor protein epitopes that activate BALB/c mouse OFA/iLRP-specific effector and regulatory T cell clones

During tumor development in mice and humans, oncofetal Ag/immature laminin receptor (OFA/iLRP)-specific Th1, CTL, and IL-10-secreting T (Ts) cells are induced. The presence of too many Ts or too few effector T cells appears to predict a poor prognosis. We established clones of OFA/iLRP-specific splenic Th1, CTL, and Ts cells from the OFA/iLRP+ MCA1315 fibrosarcoma-bearing BALB/c mice or from BALB/c mice vaccinated with 1 or 10 microg of rOFA/iLRP. The MCA1315 tumor cell-reactive T cell clones were characterized as to surface Ag phenotype, cytokine secretion profile, and specificity for OFA/iLRP presented by syngeneic splenic APC. OFA/iLRP-specific Th1 and Ts clones were established from all mice. OFA/iLRP-specific CTL could be established from all mice except for mice immunized with 10 microg of rOFA/iLRP. Analysis of the proliferation profile of the OFA/iLRP-specific clones to overlapping OFA/iLRP 12-mer peptides that spanned the OFA/iLRP protein sequence defined the epitopes to which the T cell clones responded. There was a similar spatial distribution of the epitopes to which the two types of CD8 T cell clones responded. The nonapeptide epitopes of the Ts clones were located between aa 36 and 147 of OFA/iLRP, while the epitopes of the CTL clones were located between aa 52 and 163. Even though the CTL and Ts epitopes shared part of the protein, all of the CD8 CTL epitopes were distinct and separable from those of CD8 Ts cells.

Tumor-infiltrating T lymphocytes: friends or foes?

The prognostic significance of tumor-infiltrating lymphocytes (TILs) has been a longstanding topic of debate. In cases where TILs have improved patient outcome, T lymphocytes are recognized as the main effectors of antitumor immune responses. However, recent studies have revealed that a subset of CD4(+) T cells, referred to as CD4(+)CD25(+) regulatory T cells (Treg), may accumulate in the tumor environment and suppress tumor-specific T-cell responses, thereby hindering tumor rejection. Hence, predicting tumor behavior on the basis of an indiscriminate evaluation of tumor-infiltrating T cells may result in inconsistent prognostic accuracy. The presence of infiltrating CD4(+)CD25(+) Treg may be detrimental to the host defense against the tumor, while the presence of effector T lymphocytes, including CD8(+) T cells and non-regulatory CD4(+) helper T cells may be beneficial. Enhanced recruitment of antitumor effector T lymphocytes to tumor tissue in addition to inhibition of local Treg, may therefore be an ideal target for improving cancer immunotherapy. This article reviews the antitumor functions of T-lymphocytes, with special attention given to CD4(+) regulatory T-cells within the tumor environment.

Augmented induction of CD8+ cytotoxic T-cell response and antitumour resistance by T helper type 1-inducing peptide

The effector CD8(+) T cells recognize major histocompatibility complex (MHC) class I binding altered self-peptides expressed in tumour cells. Although the requirement for CD4(+) T helper type 1 (Th1) cells in regulating CD8(+) T cells has been documented, their target epitopes and functional impact in antitumour responses remain unclear. We examined whether a potent immunogenic peptide of Mycobacterium tuberculosis eliciting Th1 immunity contributes to the generation of CD8(+) T cells and to protective antitumour immune responses to unrelated tumour-specific antigens. Peptide-25, a major Th epitope of Ag85B from M. tuberculosis preferentially induced CD4(+) Th1 cells in C57BL/6 mice and had an augmenting effect on Th1 generation for coimmunized unrelated antigenic peptides. Coimmunization of mice with Peptide-25 and ovalbumin (OVA) or Peptide-25 and B16 melanoma peptide [tyrosinase-related protein-2 (TRP-2)] for MHC class I led to a profound increase in CD8(+) T cells specific for OVA and TRP-2 peptides, respectively. This heightened response depended on Peptide-25-specific CD4(+) T cells and interferon-gamma-producing T cells. In tumour protection assays, immunization with Peptide-25 and OVA resulted in the enhancement of CD8(+) cytotoxic cell generation specific for OVA and the growth inhibition of EL-4 thymoma expressing OVA peptide leading to the tumour rejection. These phenomena were not achieved by immunization with OVA alone. Peptide-25-reactive Th1 cells counteractivated dendritic cells in the presence of Peptide-25 leading them to activate and present OVA peptide to CD8(+) cytotoxic T cells.

An Essential Role of Antigen-Presenting Cell/T-Helper Type 1 Cell-Cell Interactions in Draining Lymph Node during Complete Eradication of Class II–Negative Tumor Tissue by T-Helper Type 1 Cell Therapy

Prior studies have shown that transfer of ovalbumin (OVA)-specific T helper type 1 (Th1) cells into mice bearing MHC class II+ OVA-expressing tumor cells (A20-OVA) causes complete tumor rejection. Here we show that, although Th1 cell therapy alone was not effective against MHC class II- OVA-expressing tumor cells (EG-7), treatment of mice bearing established EG-7 tumors by i.v. transfer of Th1 cells combined with i.t. injection of the model tumor antigen OVA induced complete tumor rejection. Transferred Th1 cells enhanced the migration of tumor-infiltrating antigen-presenting cells (APC) that had processed OVA into the draining lymph node (DLN). Although transferred Th1 cells were randomly distributed in DLN, distal LN, spleen, and tumor tissue, active proliferation of Th1 cells always initiated in DLN, where Th1 cells efficiently interacted with APC that presented OVA. In parallel, OVA-tetramer+ CTLs, showing EG-7-specific cytotoxicity, were highly induced in DLN and the local tumor site. The OVA-tetramer+ CTL functioned systemically because two bilateral tumor masses were both completely rejected on treatment of one tumor. Furthermore, either active proliferation of transferred Th1 cells or generation of tetramer+ CTL was not induced in MHC class II-deficient mice and LN-deficient Aly/Aly mice. These results indicate that DLN is an indispensable organ for initiating active APC/Th1 cell interactions, which is critical for inducing complete eradication of tumor mass by tumor-specific CTL.

Tetramer-blocking assay for defining antigen-specific cytotoxic T lymphocytes using peptide-MHC tetramer

Peptide-MHC tetramers have been engineered to allow accurate detection of antigen-specific cytotoxic C lymphocytes (CTL) by flow cytometry. Here, we propose a novel use for peptide-MHC tetramers in the specific and sensitive analysis of the cytotoxic function of antigen-specific CTL by blocking MHC-restricted antigen-specific cytotoxicity. We found that pretreatment of ovalbumin (OVA)-specific CD8(+) CTL (OT-1 CTL), derived from OT-1 T-cell receptor (TCR)-transgenic mice, with OVA(257-264) peptide-H-2K(b) tetramer caused a marked inhibition of the cytotoxicity against OVA-expressing EG-7 tumor cells. OVA(257-264) peptide-H-2K(b) tetramer did not block the cytotoxicity mediated by 2C mouse (H-2(b))-derived CD8(+) CTL, which recognize allo (H-2L(d)) antigens. Moreover, OT-I CTL activity was not inhibited by an irrelevant HBV(208-216) peptide-H-2K(b) tetramer. These results indicate that the blocking of CTL activity with peptide-MHC tetramer was caused by interference with the interaction between the TCR and H-2K(b)-OVA(257-264) peptide complex, but not with the CD8-MHC class I interaction. The blocking activity of OVA(257-264) peptide-H-2K(b) tetramer was reversible because OT-I CTL pretreated with the tetramer recovered their cytotoxicity after culturing with interleukin-2 for 24 h. The same results were also demonstrated in freshly isolated, in vivo-primed OT-1 CTL sorted by the tetramer. These results demonstrate that peptide-MHC tetramer is a useful tool for defining MHC-restricted antigen-specific CTL function. Moreover, our finding implies that the measurement of CTL activity immediately after tetramer-guided sorting is not a suitable method for evaluating the function of in vivo-induced tetramer-positive CTL. We believe that the tetramer-blocking assay presented here will be useful for functionally monitor the induction of MHC-restricted antigen-specific CTL during vaccination therapy against tumor and infectious diseases.