CD4+ T cells play a crucial role for lenalidomide in vivo anti-tumor activity in murine multiple myeloma

Lenalidomide modulates the host immune response against myeloma via multiple actions. Although these effects have been elucidated in vitro, the central action of lenalidomide-mediated anti-myeloma immune response in vivo is not clear. To investigate its immune action in vivo, we selected the murine myeloma cell line 5TGM1, which is resistant to direct tumoricidal effects of lenalidomide in vitro and in immunodeficient mice, but sensitive to lenalidomide treatment in 5TGM1-bearing immunocompetent mice. Depletion of CD4⁺ T cells, but not NK cells, B cells, or CD8⁺ T cells, deprived lenalidomide of its therapeutic effects on 5TGM1-bearing immunocompetent mice. Lenalidomide significantly increased the numbers of IFN-γ-secreting CD4⁺ and CD8⁺ T cells but had no effects on NK cells and B cells in this mouse model. Lenalidomide slightly decreased the number of CD25⁺Foxp3⁺ T cells but increased perforin expression in CD8⁺ T cells in vivo. Using this mouse model for investigation of anti-tumor immune action of lenalidomide, we demonstrated that lenalidomide facilitated a type-1 anti-tumor immune response in vivo. The CD4⁺ T cell subset may play a critical role in the lenalidomide-mediated anti-myeloma immune response in vivo.     

ICOS+ Foxp3+ TILs in gastric cancer are prognostic markers and effector regulatory T cells associated with Helicobacter pylori

Regulatory T cells (Tregs) have an immunosuppressive role in the tumor microenvironment. Since effector Tregs (eTregs), which have highly suppressive functions, are located in a subpopulation of Foxp3⁺ CD4⁺ Tregs, the TCR‐inducible costimulatory receptor (ICOS) was applied as a marker of eTregs that infiltrated gastric cancer tissue and the induction pathway of ICOS⁺ Foxp3⁺ cells was analyzed by flow cytometry and immunohistochemistry. In tumor‐infiltrating lymphocytes (TILs), ICOS⁺ Foxp3⁺ CD4⁺ T cells were abundantly observed in the late stages of gastric cancer. ICOS⁺ CD4⁺ TILs exhibited the ability to produce IL‐10, but not IFN‐γ, TNF, or IL‐17 and also to suppress the proliferation of CFSE‐labeled responder CD8⁺ T cells. With the agonistic ICOS‐L protein (rICOS‐L Ig), ICOS⁺ Foxp3⁺ cells were efficiently induced from naive CD4⁺ T cells under a stimulation with TGF‐β and CD3/CD28 mAbs. Furthermore, when A*0201 PBMCs were cultured with the CMV or Melan‐A antigenic peptide and rICOS‐L Ig, the induction of CMV or Melan‐A tetramer‐binding CD8⁺ T cells, respectively, was inhibited. The expression of ICOS in Foxp3⁺ cells was closely related to plasmacytoid dendritic cells (pDCs) and their expression of ICOS‐L and TLR9 as well as Helicobacter pylori infection. Collectively, our results demonstrate the potential of ICOS as a promising target for direct Treg‐targeting therapeutic agents for gastric cancer, and that of eradicating therapy for H. pylori as an indirect immune therapy for gastric cancer.     

Vemurafenib reverses immunosuppression by myeloid derived suppressor cells

Myeloid derived suppressor cells (MDSCs) suppress innate and adaptive immunity, thereby limiting anti‐tumor immune responses in cancer patients. In patients with advanced melanoma, the phenotype and function of MDSCs remains controversial. In our study, we further explored two distinct subpopulations of MDSCs and investigated the impact of Vemurafenib on these cells. Flow cytometry analysis revealed that in comparison to healthy donors and patients with localized disease, PBMCs from patients with metastatic melanoma showed an increased frequency of CD14⁺HLA‐DR^?/low monocytic MDSCs (moMDSCs) and of a previously unrecognized population of CD14^?CD66b⁺Arginase1⁺ granulocytic MDSCs (grMDSCs). In vitro, both populations suppressed autologous T‐cell proliferation, which was tested in CFSE‐based proliferation assays. Vemurafenib treatment of melanoma patients reduced the frequency of both moMDSCs and grMDSCs. According to our in vivo finding, conditioned medium (CM) from Vemurafenib treated melanoma cells was less active in inducing moMDSCs in vitro than CM from untreated melanoma cells. In conclusion, patients with advanced melanoma show increased levels of moMDSCs, and of a population of CD14^?CD66b⁺Arginase1⁺ grMDSCs. Both MDSCs are distinct populations capable of suppressing autologous T‐cell responses independently of each other. In vitro as well as in vivo, Vemurafenib inhibits the generation of human moMDSCs. Thus, Vemurafenib decreases immunosuppression in patients with advanced melanoma, indicating its potential as part of future immunotherapies.     

HDAC5 controls the functions of Foxp3+ T‐regulatory and CD8+ T cells

Histone/protein deacetylases (HDACs) are frequently upregulated in human malignancies and have therefore become therapeutic targets in cancer therapy. However, inhibiting certain HDAC isoforms can have protolerogenic effects on the immune system, which could make it easier for tumor cells to evade the host immune system. Therefore, a better understanding of how each HDAC isoform affects immune biology is needed to develop targeted cancer therapy. Here, we studied the immune phenotype of HDAC5^–/– mice on a C57BL/6 background. While HDAC5^–/– mice replicate at expected Mendelian ratios and do not develop overt autoimmune disease, their T‐regulatory (Treg) cells show reduced suppressive function in vitro and in vivo. Likewise, CD4⁺ T‐cells lacking HDAC5 convert poorly to Tregs under appropriately polarizing conditions. To test if this attenuated Treg formation and suppressive function translated into improved anticancer immunity, we inoculated HDAC5^–/– mice and littermate controls with a lung adenocarcinoma cell line. Cumulatively, lack of HDAC5 did not lead to better anticancer immunity. We found that CD8⁺ T cells missing HDAC5 had a reduced ability to produce the cytokine, IFN‐γ, in vitro and in vivo, which may offset the benefit of weakened Treg function and formation. Taken together, targeting HDAC5 weakens suppressive function and de‐novo induction of Tregs, but also reduces the ability of CD8⁺ T cells to produce IFN‐γ.     

Expression of caspase-3 in cord blood CD34<Superscript>+</Superscript> cells during culture in vitro

Objective: To investigate the expression and significance of caspase-3 protein in CD34⁺ cells from cord blood (CB) during culturein vitro with different growth factors.Methods: RT-PCR, Western blot and flow cytometry techniques were used to detect the expression of caspase-3 in CD34⁺ CB cells during culturein vitro. Results: Caspase-3 mRNA was constitutively expressed at a low level in freshly isolated CD34⁺ cells. The expression of caspase-3 mRNA and protein was upregulated when these cells were first expanded in suspension culture with growth factors for 3 days. However, only the 32 kDa inactive caspase-3 proenzyme was detected in the freshly isolated CD34⁺ cells as well as during the first 3 days expansion with cytokines. With longer culture timein vitro, especially in the presence of the combination of IL-3, IL-6 and GM-CSF, caspase-3 was activated and a cleavage product of 20 kDa became detectable.Conclusion: Caspase-3 is involved in apoptosis of primitive CB CD34⁺ cells during expansionin vitro. The study was supported by a grant from the National Natural Science Foundation of China (No. 39928010)     

Efficacy of the antimicrobial peptide TP4 against Helicobacter pylori infection: in vitro membrane perturbation via micellization and in vivo suppression of host immune responses in a mouse model

Helicobacter pylori infection is marked by a strong association with various gastric diseases, including gastritis, ulcers, and gastric cancer. Antibiotic treatment regimens have low success rates due to the rapid occurrence of resistant H. pylori strains, necessitating the development of novel anti-H. pylori strategies. Here, we investigated the therapeutic potential of a novel peptide, Tilapia Piscidin 4 (TP4), against multidrug resistant gastric pathogen H. pylori, based on its in vitro and in vivo efficacy. TP4 inhibited the growth of both antibiotic-sensitive and -resistant H. pylori (CagA⁺, VacA⁺) via membrane micelle formation, which led to membrane depolarization and extravasation of cellular constituents. During colonization of gastric tissue, H. pylori infection maintains high T regulatorysubsets and a low Th17/Treg ratio, and results in expression of both pro- and anti-inflammatory cytokines. Treatment with TP4 suppressed Treg subset populations and pro- and anti-inflammatory cytokines. TP4 restored the Th17/Treg balance, which resulted in early clearance of H. pylori density and recovery of gastric morphology. Toxicity studies demonstrated that TP4 treatment has no adverse effects in mice or rabbits. The results of this study indicate that TP4 may be an effective and safe monotherapeutic agent for the treatment of multidrug resistant H. pylori infections.     

CIITA‐driven MHC‐II positive tumor cells: Preventive vaccines and superior generators of antitumor CD4+ T lymphocytes for immunotherapy

In our study, we have investigated whether tumors of distinct histological origin can be rejected if expressing CIITA‐driven MHC class II molecules. Moreover, we assessed whether antitumor lymphocytes generated by this approach could be used as an immunotherapeutic tool for established cancers. Stable CIITA‐transfectants of C51colon adenocarcinoma, RENCA renal adenocarcinoma, WEHI‐164 sarcoma as well as TS/A mammary adenocarcinoma were generated. Tumor cells transfectants were injected in vivo, and their growth kinetics and recipient's immune response were analyzed. Tumor rejection and/or retardation of growth was found for the first 3 CIITA‐transfected tumor cell lines and confirmed for TS/A‐CIITA. Animals rejecting CIITA‐transfected tumors acquired specific immunological memory as demonstrated by resistance to challenge with parental tumors. Adoptive cell transfer experiments demonstrated that tumor immunity correlates with the efficient priming of CD4⁺ T helper cells and the consequent activation of CD8⁺ T lymphocytes. T cells from TS/A‐vaccinated mice were used in an adoptive immunotherapy model of established tumors. The results showed the cure at early stages and significantly prolonged survival at later stages of tumor progression. Importantly, CD4⁺ T cells were clearly superior to CD8⁺ T cells in antitumor protective function. Interestingly, the protective phenotype was associated to both a Th1 and Th2 polarization of the immune effectors. These results establish the general application of our tumor vaccine model and disclose the additional application of this strategy for producing better lymphocyte effectors for adoptive antitumor immunotherapy.     

Transforming Growth Factor-β CD4+ T cells Tumor-bearing state Immunosuppression Enhanced Production of TGF-β and a Progressive Increase in TGF-β Susceptibility of Anti-tumor CD4+ T Cell Function

The present study deals with the effect of transforming growth factor-β (TGF-β) on anti-tumor immune responsiveness at various stages of the tumor-bearing state. Spleen cells from BALB/c mice bearing a syngeneic tumor (CSA1M) 1–3 wk after inoculation with CSA1M cells produced interleukin-2 (IL-2) and macrophage-activating factor (MAF)/interferon-γ (IFN-γ) upon in vitro culture without addition of exogenous tumor antigens. This lymphokine production was achieved through collaboration between anti-CSA1M CD4⁺ T cells and antigen-presenting cells that had been pulsed with CSA1M tumor antigens in vivo in the tumor-bearing state. The IL-2-producing capacity of CD4⁺ T cells reached the maximal level as early as one week after tumor implantation but decreased with the progress of tumor-bearing stages. In contrast, the capacity of CD4⁺ T cells to produce MAF/IFN-γ was not affected but was maintained at high levels even late in the tumor-bearing state. The addition of recombinant TGF-β (rTGF-β) to cultures of spleen cells from various tumor-bearing stages resulted in the suppression of lymphokine production. However, the magnitude of the TGF-β-induced suppression varied depending on which tumor-bearing stages of splenic cells were tested as a responding cell population; it was slight in cells from early (1–3 wk) tumor-bearing stages but increased in cells from donor mice at later tumor-bearing stages. Thus, spleen cells from late tumor-bearing stages with weak but significant IL-2-producing and considerable MAF/IFN-γ producing capacities failed to produce these lymphokines when rTGF-β was present in cultures. A progressive increase in the TGF-β susceptibility was also observed for IL-4-producing Th2 as well as IL-2/MAF-producing Th1 cells. In addition, increased levels of TGF-β were detected in plasma from tumor-bearing mice at late stages. Taken together, these results indicate that tumor-bearing mice exhibit enhanced production of TGF-β as well as a progressive increase in the susceptibility of anti-tumor CD4⁺ T cells to TGF-β-induced suppressive mechanisms.     

Suppression of Anti-tumor CD4+ T Cell Responsiveness in the Tumor-bearing State and Its Recovery in in vitro Culture Free of Tumor Burden

We investigated whether the responsiveness of anti-tumor CD4⁺ T cells suppressed in the tumor-bearing state is reversed in conditions free of tumor burden. Spleen cells from BALB/c mice bearing a syngeneic tumor (CSA1M) 1–3 wk after inoculation with CSA1M cells produced interleukin-2 (IL-2) and IL-4 upon in vitro culture without addition of exogenous tumor antigens. This lymphokine production was achieved through collaboration between anti-CSA1M CD4⁺ T cells and antigen-presenting cells (APC) that had been pulsed with CSA1M tumor antigens in vivo in the tumor-bearing state. However, spleen cells from late (8–10 wk) tumor-bearing stages produced reduced levels of lymphokine production despite the presence of comparable proportions of CD4⁺ T cells. Because APC in these cell populations exhibited enhanced capacities to present tumor antigens, reduced responsiveness was ascribed to the dysfunction of CD4⁺ T cells themselves. When spleen cells from early tumor-bearing mice were preincubated for 1–2 days and recultured in fresh medium, the magnitude of lymphokine production by these cells was not changed. In contrast, the same protocol of preincubation and reculture for cells from late tumor-bearing mice resulted in the recovery of anti-tumor lymphokine-producing capacity. The recovered capacity was comparable to or slightly higher than that expressed by cells from early tumor-bearing stages. Since the CD4⁺ T cell content did not significantly differ before and after preincubation, enhanced lymphokine production was due to the recovered responsiveness of anti-tumor CD4⁺ helper T cells. The recovery of anti-tumor responsiveness was also induced in vivo by tumor removal at the late tumor-bearing stage: spleen cells from mice 2–4 wk after tumor resection efficiently produced IL-2 and IL-4. These results indicate that the immunodysfunction of anti-tumor CD4⁺ T cells induced in the tumor-bearing state is reversible because release from tumor burden either by preincubation in vitro or by tumor removal in vivo results in almost complete recovery of the potent anti-tumor responsiveness initially expressed.     

Dendritic Cells Pulsed with Total Tumor RNA for Activation NK-like T Cells Against Glioblastoma Multiforme

Summary Dendritic cells (DCs) are potent antigen presenting cells and play critical role in T cell-mediated immunity. DCs have been shown to induce strong anti-tumor responses both in vitro and in vivo. Their efficacies in tumor therapy are being investigated in clinical trials. Previous evidence has shown that these DCs enhance the cytotoxicity of NK cells. We generated NK-like T cells (CD3⁺CD56⁺), a novel type of effector cells differentiated from normal lymphocyte, which is now being used for adoptive immunotherapy in clinical trials. This study aimed to elucidate the effects of NK-like T cells after co-culturing with DCs against tumor cells. The result revealed that tumor-derived RNA-pulsed DCs can enhance the immune responses of NK-like T cells against glioblastoma multiforme cell line but these effector cells did not appear to have the cytotoxic effect against normal cells (human umbilical vein endothelial cells (HUVEC) and fibroblasts) in vitro. This study may be beneficial for the development of new immunologic effector cells for using in adoptive immunotherapy for glioblastoma multiforme in the future.     

The histone demethylase Utx controls CD8+ T-cell-dependent antitumor immunity via epigenetic regulation of the effector function

CD8⁺ T cells play a central role in antitumor immune responses. Epigenetic gene regulation is essential to acquire the effector function of CD8⁺ T cells. However, the role of Utx, a demethylase of histone H3K27, in antitumor immunity remains unclear. In this study, we examined the roles of Utx in effector CD8⁺ T-cell differentiation and the antitumor immune response. In a murine tumor-bearing model, an increased tumor size and decreased survival rate were observed in T-cell-specific Utx KO (Utx KO) mice compared with wild-type (WT) mice. The number of CD8⁺ T cells in tumor-infiltrating lymphocytes (TILs) was significantly decreased in Utx KO mice. We found that the acquisition of effector function was delayed and attenuated in Utx KO CD8⁺ T cells. RNA sequencing revealed that the expression of effector signature genes was decreased in Utx KO effector CD8⁺ T cells, while the expression of naïve or memory signature genes was increased. Furthermore, the expression of Cxcr3, which is required for the migration of effector CD8⁺ T cells to tumor sites, was substantially decreased in Utx KO CD8⁺ T cells. These findings suggest that Utx promotes CD8⁺ T-cell-dependent antitumor immune responses partially through epigenetic regulation of the effector function.     

CD19+CD24hiCD38hiBregs involved in downregulate helper T cells and upregulate regulatory T cells in gastric cancer

Regulatory B cells (Bregs) play a critical role in inflammation and autoimmune disease. We characterized the role of Bregs in the progression of gastric cancer. We detected an increase in Bregs producing IL-10 both in peripheral blood mononuclear cells (PBMCs) and in gastric tumors. Multicolor flow cytometry analysis revealed that a subset of CD19⁺CD24^hiCD38^hi B cells produces IL-10. Functional studies indicated that increased Bregs do not inhibit the proliferation of CD3⁺T cells or CD4⁺ helper T cells (Th cells). However, Bregs do suppress the secretion of IFN-γ and TNF-α by CD4⁺Th cells. CD19⁺CD24^hiCD38^hiBregs were also found to correlate positively with CD4⁺FoxP3⁺ regulatory T cells (Tregs). Neutralization experiments showed that Bregs convert CD4⁺CD25⁻ effector T cells to CD4⁺FoxP3⁺Tregs via TGF-β1. Collectively, these findings demonstrate that increased Bregs play a immunosuppressive role in gastric cancer by inhibiting T cells cytokines as well as conversion to Tregs. These results may provide new clues about the underlying mechanisms of immune escape in gastric cancer.     

Chimeric antigen receptor‐engineered cytokine‐induced killer cells overcome treatment resistance of pre‐B‐cell acute lymphoblastic leukemia and enhance survival

Pre‐emptive cancer immunotherapy by donor lymphocyte infusion (DLI) using cytokine‐induced killer (CIK) cells may be beneficial to prevent relapse with a reduced risk of causing graft‐versus‐host‐disease. CIK cells are a heterogeneous effector cell population including T cells (CD3⁺ CD56^?), natural killer (NK) cells (CD3^?CD56⁺) and natural killer T (T‐NK) cells (CD3⁺ CD56⁺) that exhibit non‐major histocompatibility complex (MHC)‐restricted cytotoxicity and are generated by ex vivo expansion of peripheral blood mononuclear cells in the presence of interferon (IFN)‐γ, anti‐CD3 antibody, interleukin‐2 (IL‐2) and interleukin‐15 (IL‐15). To facilitate selective target‐cell recognition and enhance specific cytotoxicity against B‐cell acute lymphoblastic leukemia (B‐ALL), we transduced CIK cells with a lentiviral vector encoding a chimeric antigen receptor (CAR) that carries a composite CD28‐CD3ζ domain for signaling and a CD19‐specific scFv antibody fragment for cell binding (CAR 63.28.z). In vitro analysis revealed high and specific cell killing activity of CD19‐targeted CIK/63.28.z cells against otherwise CIK‐resistant cancer cell lines and primary B‐ALL blasts, which was dependent on CD19 expression and CAR signaling. In a xenograft model in immunodeficient mice, treatment with CIK/63.28.z cells in contrast to therapy with unmodified CIK cells resulted in complete and durable molecular remissions of established primary pre‐B‐ALL. Our results demonstrate potent antileukemic activity of CAR‐engineered CIK cells in vitro and in vivo, and suggest this strategy as a promising approach for adoptive immunotherapy of refractory pre‐B‐ALL.     

Adoptive transfer of ex vivo-activated memory T-cell subsets with cyclophosphamide provides effective tumor-specific chemoimmunotherapy of advanced metastatic murine melanoma and carcinoma

Autolymphocyte therapy (ALT) is adoptive cellular therapy of neoplastic disease using ex vivo activation of autologous (human) or syngeneic (murine) lymphocytes from tumor-bearing hosts (TBH) by low doses of anti-CD3 monoclonal antibody (MAb) and a mixture of previously prepared autologous cytokines (T3CS). Ex vivo activation by T3CS without tumor antigen results in expansion of CD44⁺ (memory) T cells. These memory T cells (ALT cells) mediate in vivo anti-tumor specificity and with cyclophosphamide (CY) are capable of curing metastatic disease in murine TBH. To determine whether CY could enhance the effectiveness of CD4⁺ or CD8⁺ subsets of ALT cells, C57BL/6J TBH with B16 melanoma or Lewis lung (3LL) carcinoma were treated with adoptive chemoimmunotherapy (ACIT) using CD4-depleted or CD8-depleted ALT cells and CY. ALT cells were derived from splenocytes of B16 or 3LL-TBH and activated ex vivo with T3CS. Depletion of CD4⁺ or CD8⁺ T cells was performed before or after activation with T3CS. B16-TBH or 3LL-TBH that received ACIT using CY with B16-derived or 3LL-derived CD8-depleted ALT cells, respectively, demonstrated cure of metastatic disease regardless of whether CD8⁺ T cells were depleted before or after T3CS activation. B16 or 3LL-TBH that received ACIT using CY with B16 or 3LL-derived CD4-depleted ALT cells also cured metastatic disease but only if CD4⁺ T cells were depleted after T3CS activation. Interleukin (IL)-2 added to pre-T3CS CD4-depleted ALT cells cultured with T3CS restored anti-tumor activity when combined with CY. TBH cured by ACIT using CY and ALT-cell subsets derived from syngeneic TBH with the identical tumor displayed tumor-specific immunity in rejecting a lethal challenge of identical but not reciprocal tumor. TBH given ACIT using CY and ALT-cell subsets derived from splenocytes of syngeneic TBH with reciprocal tumors rejected lethal challenges of both tumors. Tumor specificity measured by interferon (IFN)-γ and ⁵¹Cr-release assays was demonstrated in pre- or post-T3CS/CD8-depleted, post-T3CS/CD4-depleted and pre-T3CS + IL-2/CD4-depleted ALT-cell subsets. Our data demonstrate that ACIT using CY combined with ex vivo T3CS-activated CD44⁺ memory T-cell subsets conveys long-term tumor-specific immunity. © 1995 Wiley-Liss, Inc.     

Rat primary T cells expressing HTLV-I tax gene transduced by a retroviral vector: In vitro and in vivo characterization

We prepared a recombinant retroviral vector expressing the human T-lymphotropic virus type-I tax gene. Infection of WKA/H rat splenocytes yielded T-cell lines which proliferated continuously in media supplemented with exogenous interleukin-2 (IL-2) after the control cells ceased to grow. The phenotype of these cells closely resembled that of typical adult T-cell leukemia cells and tax-immortalized human T cells; i.e., positive for CD3, CD4 and IL-2 receptor α-chain. Chromosomal analysis revealed that about 10% of the tax-transduced T cells had several chromosomal abnormalities. We also performed in vivo characterization of tax-transduced splenocytes by injecting them into newborn syngeneic rats soon after in vitro infection. Maintenance of the injected tax-transduced cell population and in vivo expression of the tax gene was confirmed in the splenocytes of the injected rats by polymerase chain reaction. However, development of obvious disease was not observed in these rats for up to 18 months after inoculation. These results indicate that tax is capable of immortalizing rat mature CD4⁺ T cells in vitro but may be insufficient for full transformation of these cells in vivo. Our in vivo system using retrovirally tax-transduced rat T cells could facilitate investigation of the additional genetic events that cooperatively transform T cells transduced with tax gene. © 1996 Wiley-Liss, Inc.     

Transgenic expression of IL-33 activates CD8 T cells and NK cells and inhibits tumor growth and metastasis in mice

IL-33 is a multifunctional cytokine in immune regulation that activates Th1 cells, Th2 cells, CD8⁺ T cells and NK cells. Our study showed that transgenic expression of IL-33 attenuated tumor metastasis in the B16 melanoma and Lewis lung carcinoma (LLC) metastatic models. The percentages and cytotoxicity of CD8⁺ T cells and NK cells and their infiltration into the tumor tissues were significantly increased by the transgenic expression of IL-33 in tumor-bearing mice. Treatment with recombinant IL-33 could also increase the cytotoxicity of CD8⁺ T cells and NK cells in vitro. In addition, depletion of CD8⁺ T cells and NK cells using anti-CD8 or anti-asialo GM1 antibody abolished the pulmonary metastasis inhibition mediated by IL-33. Furthermore, IL-33 stimulated the activation of NF-κB and increased CD69 expression, which is a marker of the activated form of the two cell subsets, in CD8⁺ T cells and NK cells. Our results suggest that IL-33 stimulated NF-κB signaling and promoted the proliferation, activation and infiltration of CD8⁺ T cells and NK cells, which resulted in the inhibition of pulmonary metastasis in B16 melanoma and LLC mice models.     

Blood monocytes sample MelanA/MART1 antigen for long‐lasting cross‐presentation to CD8+ T cells after differentiation into dendritic cells

Human blood monocytes are very potent to take up antigens. Like macrophages in tissue, they efficiently degrade exogenous protein and are less efficient than dendritic cells (DCs) at cross‐presenting antigens to CD8⁺ T cells. Although it is generally accepted that DCs take up tissue antigens and then migrate to lymph nodes to prime T cells, the mechanisms of presentation of antigens taken up by monocytes are poorly documented so far. In the present work, we show that monocytes loaded in vitro with MelanA long peptides retain the capacity to stimulate antigen‐specific CD8⁺ T cell clones after 5 days of differentiation into monocytes‐derived dendritic cells (MoDCs). Tagged‐long peptides can be visualized in electron‐dense endocytic compartments distinct from lysosomes, suggesting that antigens can be protected from degradation for extended periods of time. To address the pathophysiological relevance of these findings, we screened blood monocytes from 18 metastatic melanoma patients and found that CD14⁺ monocytes from two patients effectively activate a MelanA‐specific CD8 T cell clone after in vitro differentiation into MoDCs. This in vivo sampling of tumor antigen by circulating monocytes might alter the tumor‐specific immune response and should be taken into account for cancer immunotherapy.     

Proliferation of CD4+CD25high+Foxp3+ regulatory T lymphocytes in ex vivo expanded ascitic fluid from primary and recurrent ovarian carcinoma

Objective

Regulatory T lymphocytes evoke the immune tolerance by suppressing and inactivating cytotoxic T lymphocytes. The objective of this study was to compare the proportion of regulatory T lymphocytes, precisely defined as CD4⁺CD25^high+Foxp3⁺ T lymphocytes, in primary and recurrent ovarian carcinoma before and after ex vivo expansion of ascites with interleukin-2 (IL-2).

Methods

Ascitic fluid samples were obtained from 26 patients with ovarian carcinoma. Lymphocytes were isolated from ascites and cell markers were analyzed by flow cytometry using anti-CD3/CD4/CD8/CD16/CD56/CD25 and anti-Foxp3 antibodies. Lymphocytes were incubated for 2 to 3 weeks and expanded ex vivo by IL-2 stimulation and their phenotypes were analyzed by flow cytometry.

Results

Following ex vivo expansion, ascitic fluid lymphocytes increased by a greater extent in the recurrent group than in the primary group. The proportion of ex vivo-expanded lymphocytes changed as follows; CD4⁺ T lymphocytes increased, CD8⁺ T lymphocytes decreased, and the proportion of CD3^-CD16⁺56⁺ NK cells was unchanged. The proportion of CD4⁺CD25^high+Foxp3⁺ regulatory T lymphocytes in CD4⁺ T lymphocytes increased after ex vivo expansion in both groups, but to a greater degree in the recurrent group.

Conclusion

This study showed that regulatory T lymphocytes, neither cytotoxic T lymphocytes nor NK cells, were extensively increased after ex vivo expansion, especially in recurrent ovarian carcinoma. These results may provide information that helps to guide the future development of adoptive immunotherapy against ovarian carcinoma.