Sequential involvement of two distinct CD4+ regulatory T cells during the course of transplantable tumor growth and protection from 3-methylcholanthrene-induced tumorigenesis by CD25-depletion.

The involvement of two phenotypically different regulatory T cells in different stages of tumor growth was investigated. Treatment of BALB/c mice with anti-CD25 monoclonal antibody (mAb) (PC61), but not anti-CD4 mAb (GK1.5) before RL male 1 or Meth A inoculation caused tumor rejection. On the other hand, treatment of BALB/c mice with anti-CD4 mAb (GK1.5) but not anti-CD25 mAb (PC61) on day 6 after inoculation of the same tumors caused rejection. The findings suggest that CD4+CD25+ T cells downregulated the rejection response in the early stage of tumor growth. On the other hand, putative CD4+CD25- T cells downregulated the tumor rejection response in the late stage. Both CD4+CD25+ and putative CD4+CD25- T cells appeared to inhibit the efficient generation of cytotoxic T lymphocytes (CTL). The present study also demonstrated that the treatment of BALB/c mice with anti-CD25 mAb (PC61) at 4 or 6 weeks after 3-methylcholanthrene (3-MC) inoculation retarded tumor occurrence and prolonged survival.     

The Roles of CD8+ and CD4+ Cells in Tumor Rejection

In vivo administrations of anti-Lyt-2.2 (CDS) mAb and anti-L3T4 (CD4) mAb selectively eliminated CD8⁺ cells amd CD4⁺ cells, respectively. The relative potencies of CD8⁺ cells and CD4⁺ cells and their roles in primary tumor rejections were studied by investigating the effects of these mAbs on tumor growth. CD8⁺ cells were themselves fully capable of mediating rejection in 5 different tumor rejection systems: two radiation leukemia virus (RadLV)-induced leukemias, B6RV2 and BALBRVD, a radiation-induced leukemia BALBRL♂1, and a plasmacytoma BALBMOPC-70A in CB6F₁ mice, and a Friend virus-induced leukemia B6FBL-3 in B6 mice. On the other hand, CD4⁺ cells were capable of resisting tumor growth of B6FBL-3, but not of the other four tumors. Furthermore, for efficient rejection of CB6F₁UV+^˚l sarcoma by CB6F₁ mice, synergy of CDS⁺ and CD4⁺ cells was necessary. Blocking of UV+^˚ 1 rejection was abrogated by delayed administration of anti-L3T4 (CD4) mAb but not anti-Lyt-2.2 (CDS) mAb, indicating the involvement of CD4⁺ cells in only the initial phase of rejection.     

Human epithelial ovarian carcinoma cell-derived cytokines cooperatively induce activated CD4+CD25−CD45RA+ naïve T cells to express forkhead box protein 3 and exhibit suppressive ability in vitro

Regulatory T cells play an important role in tumor escape from host antitumor immunity. Increased frequencies of CD4⁺CD25⁺ regulatory T cells have been documented in the tumor sites, malignant effusions, and peripheral blood of patients with ovarian carcinoma. However, the mechanism involved remains unclear. In the present study, we collected high-purity human CD4⁺CD25⁻CD45RA⁺ naïve T cells by microbead cell separation. These cells did not express FOXP3 by single-cell analysis, and few cells expressed FOXP3 when they were activated with anti-CD3/CD28 dual signal. However, more cells expressed FOXP3 when the supernatant of human epithelial ovarian carcinoma cell culture was added, yet not the supernatant of normal human ovarian surface epithelia cell culture. Neutralization assays revealed that neutralizing antibody against transforming growth factor β (TGF-β), interleukin-10, and interleukin-4 did not abrogate elevated FOXP3 expression induced by carcinoma cell culture supernatant, whereas neutralizing leukemia inhibitory factor (LIF) partially abrogated FOXP3 expression, but LIF alone could not increase FOXP3 expression in activated naïve T cells. Further, an in vitro coculture suppression assay showed that these cells could suppress the proliferation of autologous CD4⁺CD25⁻CD45RA⁻ T cells. In summary, our findings show that ovarian carcinoma cells are able to induce expression of FOXP3 and exhibit suppressive ability in activated naïve T cells by producing soluble substances, and multiple cytokines involve in the induction of FOXP3 expression. ( Cancer Sci 2009)     

Bispecific Antibody-directed Antitumor Activity of Human CD4+ Helper/Killer T Cells Induced by Anti–CD3 Monoclonal Antibody plus Interleukin 2

Freshly isolated human CD4⁺ T cells can not respond to recombinant interlenkin 2 (rIL–2) because of their lack of p75 IL–2 receptor expression. However, we succeeded In inducing a marked proliferation of purified CD4⁺ T cells by activation with rIL–2 plus anti–CD3 monoclonal antibody (mAb) cross–linked to a plastic plate. The proliferated CD4⁺ T cells produced a significant amount of IL–2 upon stimulation with phorbol ester plus A23187. Interestingly, CD4⁺ T cells activated with anti–CD3 mAb plus rIL–2 revealed a strong cytotoxic activity against Fc receptor (FcR)–positive tumor cells in the presence of anti–CD3 mAb. Moreover, the CD4⁺ T cells could lyse FcR–negative glioma cells by targeting with bispecific mAb containing anti–CD3 mAb and anti–glioma mAb. Thus, we demonstrated that rIL–2 and immobilized anti–CD3 mAb allowed the rapid generation of human CD4⁺ helper/killer T cells, which may be useful for the development of a new adoptive tumor immunotherapy.     

Adult T-cell leukemia/lymphoma cells from blood and skin tumors express cytotoxic T lymphocyte-associated antigen-4 and Foxp3 but lack suppressor activity toward autologous CD8+ T cells

Adult T cell leukemia/lymphoma (ATL) cells share the CD4⁺CD25⁺ phenotype with regulatory T (Treg) cells. However, it is still controversial whether ATL cells are Treg cells. The aim of the present study was to investigate the Treg nature of ATL cells obtained from peripheral blood and skin tumors in terms of their phenotype and function. By flow cytometry and immunohistochemistry, the expression of the Treg-associated molecule cytotoxic T lymphocyte-associated antigen (CTLA)-4 and Foxp3 was examined in freshly isolated circulating and skin-infiltrating tumor cells from 21 ATL patients with skin eruptions. The expression of CTLA-4 on freshly isolated circulating tumor cells was elevated in two of 15 patients, and Foxp3 was expressed intracytoplasmically at high levels in three of nine patients. In five of the patients examined, skin-infiltrating tumor cells bore variously elevated CTLA-4 with high Foxp3 expression. The potentiality of ATL cells as Treg cells was further addressed by stimulating ATL cells with anti-CD3/CD28 monoclonal antibodies and monitoring CTLA-4 expression. With the stimulation, even CTLA-4-low ATL cells expressed higher levels of CTLA-4 than normal CD4⁺CD25⁺ cells. To study function, ATL cells isolated from blood and skin tumors were tested for their ability to suppress the proliferation of autologous CD8⁺ T cells stimulated with allogeneic lymphocytes. Despite the expression of CTLA-4 and Foxp3, these tumors were incapable of suppressing the proliferation of autologous CD8⁺ T cells. ATL cells are phenotypically Treg cells in at least some patients, but lack immunoregulatory functions, at least toward CD8⁺ T cells. ( Cancer Sci 2008; 99: 98–106)     

Murine Asialo GM1+CD8+ T Cells as Novel Interleukin-12-responsive Killer T Cell Precursors

Freshly isolated CD8⁺ T cells, but not CD4⁺ T cells, contained 20–30% of asialo GM1⁺ (ASGM1⁺) T cells which were distinct from ASGM1⁺NK1.1⁺ natural killer cells. This novel ASGM1⁺CD8⁺ T cell subpopulation showed a strong proliferative response to interlenkin-12 (IL-12) in the presence of IL-2. Culture of ASGM1⁺CD8⁺ T cells with IL-12 plus IL-2 allowed the generation of anomalous killer T cells concomitantly with the accumulation of cytolytic molecules. Moreover, ASGM1⁺CD8⁺ T cells produced high levels of interferon-γ (IFN-γ), but not IL-4, upon stimulation with IL-12 plus IL-2. Such immune responses were not observed in ASGM1⁻ CD8⁺ T cell snbpopulations constituting the majority of CD8⁺ T cells. These results demonstrated that ASGM1⁺CD8⁺ T cells are a novel subpopulation of IL-12-responsive and IFN-γ-producing killer T cell precursors.     

Combinations of tumor-specific CD8+ CTLs and anti-CD25 mAb provide improved immunotherapy

One new approach to cancer therapy is based on the adoptive transfer of tumor-specific cytotoxic T cells and anti-CD25 antibodies. In the present study, CD8+ and IFN-gamma secreting T lymphocytes (CTLs) were enriched as tumor-specific cytotoxic T cells from spleen lymphocytes of mice bearing the Renca tumor (a murine renal carcinoma line originating from a BALB/c mouse) after stimulation with tumor cells. An anti-CD25 IL-2Ralpha(anti-CD25) mAb from hybridoma PC61 was used for depletion for CD4(+)CD25(+) regulatory T (Treg) cells. Treatment-efficacy for tumor-bearing mice was compared using 4 systems: 1, whole spleen lymphocytes stimulated with tumor cells in vitro from tumor-bearing mice; 2, CTLs; 3, anti-CD25 mAbs; 4, CTLs and anti-CD25 mAbs. At the 50th day after tumor inoculation, in the group which received anti-CD25 mAb for depletion of T cells and inoculation of CTLs, tumors had disappeared and no re-growth was observed. In contrast, all mice of the non-treated and other three groups, treated with whole spleen cells alone, CTLs alone and anti-CD25 mAb alone, had died. These results showed that a combination of Treg cell-depletion using anti-CD25 mAbs and CTL administration is a feasible approach for treatment of cancers which warrants further exploration in the clinical setting.     

Cytotoxic Activity of CD4+ T Cells against Autologous Tumor Cells

The ⁵¹Cr-release assay is mostly applied to detecting the cytotoxic activity of CD8⁺ T cells, and little is known about the activity of CD4⁺ T cells. Therefore, the correlation between the cytotoxic activity of CD4⁺ or CD8⁺ T cells and the incubation period with autologous tumor cells was analyzed by two methods. The incubation periods were 4 and 20 h (4 h and 20 h assay) for the ⁵¹Cr-release assay. Eight pairs of tumor cells and T cells were assayed. T cells were fractionated into CD4⁺ and CD8⁺ T cells by using magnetic beads and panning methods, and those cells were activated by culture with recombinant interleukin-2 and immobilized anti-CD3 monoclonal antibody. In 6 out of 8 cases, no cytotoxic activity of CD4⁺ T cells was detected by the 4 h assay, whereas cytotoxic activity was detected in all cases in the 20 h assay. The cytotoxic activities in 20 h assay of CD4⁺ T cells were increased 67-fold in comparison with the activities in 4 h assay (range: 5–197). In the case of CD8⁺ T cells, cytotoxic activities were detected in 6 out of 8 cases in the 4 h assay. The lytic unit ratio of CD4⁺ and CD8⁺ T cells was calculated as 1.5 in the 20 h assay (range: 0.2->7.2) versus 0.4 in the 4 h assay (range: < 0.1–1.3). Cytotoxic activities in colorimetric assay using Crystal Violet with a 24 h incubation were similar to those in the 20 h ⁵¹Cr-release assay in all eight cases. These results indicate that CD4⁺ T cells have cytotoxic activity as strong as that of CD8⁺ T cells towards autologous tumor cells.     

Histocompatibility Leukocyte Antigen-A2-restricted and Tumor-specific Cytotoxic T Lymphocytes from Tumor-infiltrating Lymphocytes of a Patient with Testicular Embryonal Cancer

T lymphocytes play an important role in tumor rejection. To understand T cell-mediated specific immunity at the tumor site of testicular embryonal cancer, we investigated whether interleukin-2 (IL-2)-activated tumor-infiltrating lymphocytes (TIL) of a patient with testicular embryonal cancer show histocompatibility leukocyte antigen (HLA)-class I-restricted and tumor-specific cytotoxicity. We established a CD3⁺CD4^-CD8⁺ cytotoxic T lymphocyte (CTL) line from the IL-2-activated TIL of a 37-year-old patient with testicular embryonal cancer. A 6 h ⁵¹Cr-release assay was performed to measure the cytotoxicity of the CTL. The CD3⁺CD4^-CD8⁺ CTL line showed cytotoxicity against HLA-A2⁺ tumor cells, including freshly isolated autologous tumor cells, adenocarcinoma cell lines from various organs (lung, breast, pancreas, colon and kidney) and squamous cell carcinomas (esophagus and oral cavity). No other cell lines examined, including an autologous tumor cell line and HLA-A2" tumor cell lines, were lysed by this CTL line. These results suggest the existence of HLA-A2-restricted and tumor-specific CTL at the tumor site of testicular embryonal cancer.     

Sequential T Cell Response Involved in Tumor Rejection of Sarcoma, Meth A, in Syngeneic Mice

We investigated the type of T cell response involved in Meth A tumor rejection in primary immune and hyperimmune syngeneic mice. It was found that a CD4⁺ T cell-mediated delayed-type hypersensitivity (DTH) response activating non-specific killer cells such as macrophages, NK and LAK cells, without a specific CD8⁺ cytotoxic T lymphocyte (CTL) response, was the major immune response leading to Meth A tumor rejection in primary immune mice. In contrast, the specific CD8⁺ CTL response was the major response leading to the tumor rejection, in addition to CD4⁺ T cell-mediated DTH response, in hyperimmune mice. Analysis of CD4⁺ T cell clones established from primary immune and hyperimmune spleen cells indicated that a CD4⁺ T cell clone (C9) of primary immune mice (although only one clone was established) was of Th1 type, and induced cytotoxicity in accessory cells by classic DTH in vitro. Eight CD4⁺ T cell clones were established from hyperimmune spleen cells. Six out of the eight clones were of the Th2 type and two were Th0-like. However, no Th1-type CD4⁺ T cell clone was established from hyperimmune spleen cells. All of these CD4⁺ T cell clones, even the Th2-type clones, were capable of inducing cytotoxicity in vitro in T cell-depleted accessory cells, as in an in vitro DTH response. We postulate on the basis of these results that the T cell response leading to Meth A tumor rejection in vivo sequentially changed from a CD4⁺ T cell-mediated classic DTH response to a CD8⁺ CTL response, in addition to a cellular response mediated probably by Th2-type cells, during the process of repeated immunization.     

Macrophage–T Cell Interaction Is Essential for the Induction of p75 Interleukin 2 (IL–2) Receptor and IL–2 Responsiveness in Human CD4+ T Cells

Fresh human CD8⁺ T cells showed a strong proliferative response to a high concentration of interleukin 2 (IL–2) in the absence of macrophages. In contrast, CD4⁺ T cells revealed no significant IL–2 responsiveness in the absence of macrophages. However, if CD4⁺ T cells were cocultured with macrophages, they showed higher proliferative response to IL–2 than CD8⁺ T cells. In accordance with the magnitude of IL–2 responsiveness, freshly isolated CD8⁺ T cells expressed significant amounts of p75 IL–2 receptor, while fresh CD4⁺ T cells did not express p75 IL–2 receptor. The expression of p75 IL–2 receptor on CD4⁺ T cells was induced by coculture with macrophages. The macrophage–induced p75 IL–2 receptor acquisition was blocked by monoclonal antibody (inAh) against class II antigen. Moreover, the addition of anti–CD4 mAb or anti–class II mAb to the culture caused a great inhibition of IL–2 responsiveness of CD4⁺ T cells. These results strongly suggest that macrophage–T cell interaction through CD4 and/or class II molecules is essential for the expression of p75 IL–2 receptor and IL–2 responsiveness in human CD4⁺, but not CD8⁺ T cells.     

Anti-OX40 monoclonal antibody therapy in combination with radiotherapy results in therapeutic antitumor immunity to murine lung cancer

The therapeutic effect of agonistic anti-OX40 (CD134) monoclonal antibody (mAb) in combination with radiotherapy was evaluated in a murine lung cancer model. After intradermal transplantation of ovalbumin (OVA)-transfected Lewis lung carcinoma, C57BL/6 mice were irradiated locally with a single dose of 20 Gy in combination with an intratumoral injection of anti-OX40 mAb at 50 µg on day 4 after transplantation, which is when the major axis of the inoculated tumor reached a diameter of 7–9 mm. On days 8, 11, and 14, the tumor-bearing mice were further treated with the same dose of anti-OX40 mAb. Anti-OX40 mAb in combination with radiotherapy prolonged survival and provided greater efficacy than either single treatment against well-established tumors. An in vivo depletion study suggested that therapeutic immunity was mainly CD8⁺ T-cell dependent. OX40⁺CD8⁺ T cells were augmented in draining lymph nodes obtained from irradiated mice compared with those from non-irradiated mice. OVA-major histocompatibility complex tetramer⁺ CD8⁺ T cells had been strongly recruited to the draining lymph nodes obtained from mice treated with anti-OX40 mAb in combination with radiotherapy, and strong antigen-specific cytotoxicity was confirmed by a ⁵¹Cr-release assay. Moreover, a tumor-rechallenge model indicated that this combination therapy induced durable tumor immunity. Thus, anti-OX40 mAb in combination with radiotherapy may potentially help the management of patients with lung cancer. ( Cancer Sci 2008; 99: 361–367)     

Tumor rejection by in vivo administration of anti-CD25 (interleukin-2 receptor alpha) monoclonal antibody.

Immune regulation has been shown to be involved in the progressive growth of some murine tumors. In this study, we demonstrated that a single in vivo administration of an amount less than 0.125 mg of anti-CD25 interleukin 2 receptor alpha monoclonal antibody (mAb; PC61) caused the regression of tumors that grew progressively in syngeneic mice. The tumors used were five leukemias, a myeloma, and two sarcomas derived from four different inbred mouse strains. Anti-CD25 mAb (PC61) showed an effect in six of the eight tumors. Administration of anti-CD25 mAb (PC61) caused a reduction in the number of CD4+ CD25+ cells in the peripheral lymphoid tissues. The findings suggested that CD4+ CD25+ immunoregulatory cells were involved in the growth of those tumors. Kinetic analysis showed that the administration of anti-CD25 mAb (PC61) later than day 2 after tumor inoculation caused no tumor regression, irrespective of depletion of CD4+ CD25+ immunoregulatory cells. Two leukemias, on which the PC61-treatment had no effect, seemed to be incapable of eliciting effective rejection responses in the recipient mice because of low or no antigenicity.     

Analysis of CD8 T-cell response by IFNgamma ELISPOT and H-2L(d)/pRL1a tetramer assays in pRL1a multiple antigen peptide-immunized and RL male 1-bearing BALB/c and (BALB/c x C57BL/6) F(1) mice

We previously identified an H-2L^d-binding peptide pRL1a (IPGLPLSL) on RL male 1 that is predominantly recognized by cytotoxic T-lymphocytes (CTLs). MAP is a multibranched lysine core with antigenic peptides. Immunization of BALB/c mice with pRL1a MAP effectively induced pRL1a CTLs. Here, we demonstrate the presence of pRL1a-recognizing CD8⁺ T-cells in pRL1a MAP-immunized and RL male 1-bearing BALB/c and (BALB/ cxC57BL/6)F₁ mice by using IFNγ ELISPOT and H-2L^d/pRL1a tetramer assays. A few IFNγ ELISPOTs and no tetramer-positive cells were detected ex vivo in spleen cells from BALB/c mice immunized with pRL1a MAP. After a single in vitro stimulation with RL male 1, 432 and 741 IFNγ ELISPOTs/10⁵ cells were detected and tetramer-positive CD8⁺ T-cells occurred at relative frequencies of 5.7% and 30.8% in splenic CD8⁺ T-cells from mice that had been doubly and triply immunized, respectively, against pRL1a MAP. Tetramer-positive cells displayed two distinct cell populations, CD62L^low and CD62L^high. Secondary in vitro stimulation expanded CD62L^high cells more efficiently than CD62L^low cells. Furthermore, a higher frequency of IFNγ-producing and tetramer-positive CD8⁺ T-cells was detected ex vivo in RL male 1-bearing semi-allogeneic (BALB/cxC57BL/6)F₁ than in BALB/c mice on day 14 after tumor inoculation.     

Cytotoxicity of Histocompatibility Leukocyte Antigen–DR8–restricted CD4+ Killer T Cells against Human Autologous Squamous Cell Carcinoma

Although CD8⁺ killer T cells reacting against human autologous tumor cells have recently been studied in detail, little is known about the cytotoxic mechanism of CD4⁺ T cells against such tumor cells. In order to investigate this, we have established CD4⁺ cytotoxic T lymphocyte TcOSC–20 lines. TcOSC–20 showed selective cytotoxic activity against autologous OSC–20 cells, derived from a cancer of the tongue, in an HLA–DR–restricted fashion. HLA–DR8 (DRB1* 08032) is the only DR molecule expressed on OSC–20 cells, and anti–DRS monoclonal antibody could inhibit the Cytotoxicity, suggesting that HLA–DRB1^★ 08032 is the tumor rejection antigen–presenting moleculeto TcOSC–20. The Fas ligand was expressed on TcOSC–20 lines, and its expression was induced upon mixed lymphocyte–tumor cell culture of autologous peripheral blood lymphocytes. Furthermore, the Cytotoxicity of TcOSC–20 was inhibited by anti–Fas ligand antibody.These data imply that TcOSC–20 lines recognize the tumor antigenic peptide presented by HLA–DR8, and exert Cytotoxicity against autologous tumor cells via a Fas–mediated cytotoxic pathway.     

Interleukin-12 Augments the Generation of Autologous Tumor-reactive CD8+ Cytotoxic T Lymphocytes from Tumor-infiltrating Lymphocytes

Human tumor-infiltrating lymphocytes (TIL) were obtained from breast cancer, renal cancer or neuroblastoma to investigate the generation of autologous tumor-reactive CD8⁺ cytotoxic T lymphocytes (CTL). When TIL were cultured with interleukin (IL)-2 (100 U/ml), the growth of TIL peaked around 8–10 days after the initiation of culture. In contrast, the proliferation of TIL cultured with IL-2 plus IL-12 peaked around 4–5 days after culture and tumor cells rapidly disappeared from the culture. To determine the generation of autologous tumor-reactive CD8⁺ CTL, TIL-derived CD8⁺ T cells were separated by FACStar. Both IL-2-activated and IL-2 plus IL-12-activated TIL-CD8⁺ T cells showed the same level of lymphokine-activated killer activity against a variety of tumor cells. However, TIL-CD8⁺ T cells activated with IL-2 plus IL-12 revealed greatly augmented cytotoxicity against autologous tumor cells compared with that induced by IL-2 alone. The autologous tumor cell-killing activity of TIL-CD8⁺ CTL was significantly inhibited by the addition of F(ab)₂ anti-CD3 monoclonal antibody, indicating that these CTL recognize autologous tumor antigen through T cell receptor. These results imply that IL-12 is a novel cytokine which facilitates the generation of autologous tumor-reactive CD8⁺ CTL from TIL.     

Selective Suppression of the Generation of Anti-tumor L3T4+ but Not of Lyt-2+ T Cell-mediated Immunity in the Tumor-hearing State

C3H/He mice hyperimmune against syngeneic MH134 hepatoma were prepared by intradermal (id) inoculation of viable tumor cells followed by surgical resection of the tumor and by repeated id challenges with viable tumor cells. Winn assays performed utilizing spleen cells from these mice have revealed that both Lyt-2⁺ and L3T4⁺ T cell subsets from MH134-hyperimmune mice produced complete tumor protection. The in vivo tumor-neutralizing activity was also found in spleen cells from tumor-bearing mice at various times after id implantation of MH134 tumor cells. However, in contrast to comparable tumor-neutralization by Lyt-2⁺ and L3T4⁺ T subsets from hyperimmune mice, only the Lyt-2⁺ T cell subset from tumor-bearing mice was capable of mediating the in vivo protective immunity. L3T4⁺ T cell-mediated immunity was not detectable in the tumor-bearing state irrespective of the length of the sensitization period with a primary growing tumor, but emerged in the mice which resisted the first tumor challenge after the resection of the primary tumor. These results indicate that the emergence of L3T4⁺ T cell-mediated anti-tumor immunity is stage-dependent and the Lyt-2⁺ T cells represent the main functional subset in the tumor-bearing state, although both subsets of T cells are potentially capable of effecting anti-tumor in vivo immunity. The results are discussed in relation to the selective suppression of the L3T4⁺ but not of Lyt-2⁺ T cell function in the tumor-hearing state.     

Glucocorticoid-induced tumor necrosis factor receptor stimulation enhances the multifunctionality of adoptively transferred tumor antigen-specific CD8+ T cells with tumor regression

We have reported for the first time the significance of effector T-cell multifunctionality in antitumor immunity, suggesting that the appearance of multifunctional/polyfunctional tumor-specific CD8⁺ T cells in vivo is a critical determinant of the success of antitumor immunotherapy, and a strategy to induce multifunctionality in effector cells is required for the successful immunotherapy of hosts with progressing tumor. Glucocorticoid-induced tumor necrosis factor receptor (GITR) stimulation has been shown to enhance antitumor immune response. However, its functional impact on adoptively transferred T cells remains unclear. Here, we analyzed the impact of GITR stimulation in vivo on the functional profiles of adoptively transferred CD8⁺ T cells specific for murine fibrosarcoma CMS5. GITR stimulation was found to enhance multifunctionality (interferon (IFN)-γ and tumor necrosis factor (TNF)-α production and CD107a mobilization as a degranulation marker) in transferred cells at the single-cell level. These cells exhibited upregulated expression of CD25 in draining lymph nodes and increased infiltration in tumor. Mice that received T-cell therapy with GITR stimulation showed reduced Foxp3⁺CD4⁺ T cells among tumor infiltrating lymphocytes and increased in vivo cytotoxic T lymphocytes (CTL) activity even with progressing tumor, resulting in enhanced tumor regression. These data strengthen the idea that effector T-cell multifunctionality is a sensitive immune correlate for successful immunotherapy against malignancy and provide an immunological rationale for effective T-cell therapy combined with GITR stimulation. ( Cancer Sci 2009; 100: 1317–1325)     

Proportion of CD4+CD25+ regulatory T cell is increased in the patients with ovarian carcinoma

Objective: To study the frequency of the CD4⁺CD25⁺ regulatory T cells (Tregs) in the patients with ovarian carcinoma and its possible mechanism. Methods: The percentages of CD4⁺CD25⁺ Tregs in the peripheral blood lymphocytes (PBLs), tumor infiltrating lymphocytes (TILs) and tumor associated lymphocytes (TALs) from 13 patients with ovarian carcinoma and in the PBLs from 14 healthy women were determined by flow cytometry. The expression of CD69 on CD4⁺PBLs from the patients was detected. PBLs from healthy women were cultured in complete RPMI 1640 containing the supernatant from SKOV3 cell line with or without PHA (phytohemagglutinin) stimulation for 72 hours, then the percentage of CD4⁺CD25⁺ T cells was detected. Results: CD4⁺CD25⁺ Tregs in the PBLs from patients with ovarian carcinoma were significantly increased compared with those from the control. The percentage of CD4⁺CD25⁺ Tregs in TILs was higher than that in PBLs and TALs from the patients, but not significantly. The expression of CD69 on CD4⁺PBLs from the patients was negative. The percentages of CD4⁺CD25⁺ T cells in PBLs cultured with SKOV3 supernatant elevated significantly compared with those without supernatant whether PHA was added or not (P = 0.001 and 0.001, respectively). Conclusion: There is an increasing of the proportion of CD4⁺CD25⁺ Tregs in PBLs, TILs and TALs of the patients with ovarian carcinoma, which probably results from up-regulation of soluble factor secreted by ovarian carcinoma cells.     

Natural Antigenic Peptides from Squamous Cell Carcinoma Recognized by Autologous HLA-DR8–restricted CD4+ T Cells

A large number of human tumor antigens recognized by CD8⁺ cytotoxic T lymphocytes (CTL) have been identified. Some of them have been employed in clinical trials and have achieved some objective responses. However, little is known about those that are recognized by CD4⁺ T cells, except for a very few that were identified from melanomas. Previously, we reported that an oral squamous cell carcinoma (SCC) cell line, OSC–20, was effectively lysed by HLA-DRB1·08032 (HLA-DRS)-restricted autologous CD4⁺ T cell line, TcOSC–20. In this study, we performed two steps of chromatographic purification of the tumor cell lysate in combination with mass spectrometry. We found one reverse-phase high-performance liquid chromatography (RP-HPLC) fraction that was effectively recognized by the T cells. We analyzed the fraction by nano-liquid chromatography/electrospray ionization ion trap mass spectrometry (LC/MS/MS) and found six representative ions. We could determine the primary amino acid sequence of each of the six ions. Three of them contained a potential HLA-DR8 binding motif, and TcOSC–20 showed a rather strong cytotoxic response to one of the synthetic pep tides, namely, amino acid residues 321–336 of human a-enolase. Thus, several gene products of squamous cancer cells are endogenously processed and may be presented on HLA class II molecules, so that they could constitute target molecules for autologous CD4⁺ T cells.