Neoadjuvant chemoradiotherapy of pancreatic cancer induces a favorable immunogenic tumor microenvironment associated with increased major histocompatibility complex class I-related chain A/B expression.

BACKGROUND: Damage-associated molecular patterns (DAMPs) are related to immune responses in malignant tumors including tumor-infiltrating lymphocytes (TILs). The aim of the present study was to determine the relationship between expression of components of DAMPs and TILs in pancreatic cancer patients who underwent neoadjuvant chemoradiotherapy (NACRT) versus those who did not. METHODS: NACRT was administered to 51 patients with borderline-resectable pancreatic cancer and not to 33 patients with resectable pancreatic cancer. Resected specimens were analyzed for the presence of DAMPs, major histocompatibility complex class I-related chain A/B (MICA/B), and CD8+ TILs, CD4+ TILs, and forkhead box P3 positive (Foxp3+ ) TILs. The Treg/TIL ratio was obtained by dividing the number of Foxp3+ TILs, a surrogate for regulatory T cells, by the sum of CD8+ and CD4+ TILs. RESULTS: Overexpression of calreticulin, Hsp70, and MICA/B were all significantly correlated with NACRT administration. In the NACRT group, high MICA/B expression was associated with a low Treg/TIL ratio, indicating a favorable immunogenic tumor microenvironment. Patients with a lower Treg/TIL ratio had longer survival. CONCLUSIONS: Overexpression of MICA/B, a component of DAMPs induced by NACRT, may play an important role in acquiring a favorable immune response for pancreatic cancer which contributes to longer survival, suggesting the potential of immunotherapy of this recalcitrant disease, especially for patients with overexpression of DAMPs.

Essential role of the IRF8-KLF4 transcription factor cascade in murine monocyte differentiation.

Monocytes regulate host defenses, inflammation, and tissue homeostasis. The transcription factor interferon regulatory factor-8 (IRF8) stimulates monocyte/macrophage differentiation, yet genome-wide understanding of the differentiation program initiated by IRF8 is lacking. By combining chromatin immunoprecipitation sequencing with gene expression profiling, we show that during IRF8-dependent monocyte differentiation, IRF8 binding occurs at both promoter-proximal and promotor-distal regions together with the transcription factor PU.1 and is associated with gene induction. Many of the promoter-distal IRF8 binding sites show an increase in histone H3 lysine 4 monomethylation, a signature for enhancers. However, about half the IRF8-induced genes were not bound by IRF8, suggesting the involvement of downstream transcription factors. Analysis of DNA motifs in cis-regulatory elements of these indirect IRF8 target genes predicted that Krüppel-like factor-4 (KLF4)-essential for Ly6C(+) monocyte development-is one such factor. Indeed, monocyte development in Irf8(-/-) mice is as defective as that in Klf4(-/-) chimeric mice. Moreover, Irf8(-/-) monocyte-dendritic cell progenitors do not express Klf4 messenger RNA. Introduction of KLF4 into an Irf8(-/-) myeloid progenitor cell line induced a subset of IRF8 target genes and caused partial monocyte differentiation. Taken together, our present results uncover genome-wide behavior of IRF8 and identify an IRF8-KLF4 axis that operates during monocyte differentiation.

Immunological impact of neoadjuvant chemoradiotherapy in patients with borderline resectable pancreatic ductal adenocarcinoma.

BACKGROUND: Little is known about the immunological effect of neoadjuvant chemoradiotherapy (NACRT) in the tumor microenvironment of pancreatic ductal adenocarcinoma. The objective of this study was to examine the immunological modifications induced by NACRT in patients with pancreatic cancer. METHODS: Fifty-two patients with pancreatic cancer who underwent surgical resection were enrolled in this study. NACRT was administered to 22 patients, whereas the other 30 patients underwent surgical resection without NACRT. The resected tumor specimens were analyzed for the presence of tumor-infiltrating lymphocytes by using immunohistochemical staining for CD4, CD8, CD68, CD163, Foxp3, and major histocompatibility complex class I (MHC class I) antigen. RESULTS: The number of CD4+ and CD8+ lymphocytes was significantly higher in patients who received NACRT than in those who did not receive NACRT. No significant difference in MHC class I expression was observed between the groups. In the NACRT group, patients with a high accumulation of CD8+ cells experienced longer overall survival than those with a low number of CD8+ cells. CONCLUSIONS: NACRT may induce the accumulation of CD4+ and CD8+ cells in the tumor microenvironment and a high accumulation of CD8+ cells might be a good prognostic marker for pancreatic cancer treated with NACRT.

Exclusive localization of carbonic anhydrase in bacteriocytes of the deep-sea clam Calyptogena okutanii with thioautotrophic symbiotic bacteria.

Deep-sea Calyptogena clams harbor thioautotrophic intracellular symbiotic bacteria in their gill epithelial cells. The symbiont fixes CO2 to synthesize organic compounds. Carbonic anhydrase (CA) from the host catalyzes the reaction CO2 + H2O ↔ HCO3(-) + H(+), and is assumed to facilitate inorganic carbon (Ci) uptake and transport to the symbiont. However, the localization of CA in gill tissue remains unknown. We therefore analyzed mRNA sequences, proteins and CA activity in Calyptogena okutanii using expression sequence tag, SDS-PAGE and LC-MS/MS. We found that acetazolamide-sensitive soluble CA was abundantly expressed in the gill tissue of C. okutanii, and the enzyme was purified by affinity chromatography. Mouse monoclonal antibodies against the CA of C. okutanii were used in western blot analysis and immunofluorescence staining of the gill tissues of C. okutanii, which showed that CA was exclusively localized in the symbiont-harboring cells (bacteriocytes) in gill epithelial cells. Western blot analysis and measurement of activity showed that CA was abundantly (26-72% of total soluble protein) detected in the gill tissues of not only Calyptogena clams but also deep-sea Bathymodiolus mussels that harbor thioautotrophic or methanotrophic symbiotic bacteria, but was not detected in a non-symbiotic mussel, Mytilus sp. The present study showed that CA is abundant in the gill tissues of deep-sea symbiotic bivalves and specifically localizes in the cytoplasm of bacteriocytes of C. okutanii. This indicates that the Ci supply process to symbionts in the vacuole (symbiosome) in bacteriocytes is essential for symbiosis.

Intranasal administration of semaphorin-3A alleviates sneezing and nasal rubbing in a murine model of allergic rhinitis.

Sneezing and persistent itching of the nasal mucosa are distressing symptoms of allergic rhinitis (AR). Recent studies have revealed that hyperinnervation of sensory neurons in the nasal turbinate is one of the underlying causes of sneezing and itching. Since Semaphorin-3A (Sema3A) has been previously shown to restrict innervation of sensory neurons, it is presumed that reduced Sema3A expression in the nasal mucosa might contribute to the hypersensitivity. Analysis of the mouse model of ovalbumin-sensitized AR demonstrated a decreased expression of Sema3A in the nasal epithelium, which was accompanied by an increased nerve fiber density in the lamina propria of the turbinate. In rescue experiments, intranasal administration of recombinant Sema3A in the AR model mice alleviated sneezing and nasal rubbing symptoms. In addition, histological examinations also revealed that nerve fiber density was decreased in the lamina propria of the Sema3A-treated nasal turbinate. These results suggest that the nasal hypersensitivity of AR may be attributed to reduction of Sema3A expression and intranasal administration of Sema3A may provide a novel approach to alleviate the allergic symptoms for AR treatment.

Draft Genome Sequence of Rhodococcus aetherivorans JCM 14343T, a Bacterium Capable of Degrading Recalcitrant Noncyclic and Cyclic Ethers.

Here, we report the draft genome sequence of Rhodococcus aetherivorans JCM 14343T, which possesses the versatile ability to degrade recalcitrant noncyclic and cyclic ether compounds. The 4.2-Mbp genome of this bacterium contains alkane hydroxylase and propane monooxygenase genes involved in the degradation of noncyclic and cyclic ethers, respectively.

Effect of BSA antigen sensitization during the acute phase of influenza A viral infection on CD11c+ pulmonary antigen presenting cells.

BACKGROUND: Influenza A viral infection is concerned with induction of asthma. CD11c+ pulmonary antigen presenting cells (APCs) play a central role in sensitization with inhaled antigens during the acute phase of influenza A viral infection and also reside on bronchial epithelium for the long term after sensitization. To investigate the role of CD11c+ pulmonary APCs in the inhaled antigen sensitization during the acute phase of influenza A viral infection, we analyzed their function. METHODS: Mice were infected with influenza A virus and were sensitized intranasally with BSA/alum during the acute phase of influenza A viral infection. Expression of surface antigens on CD11c+ pulmonary APCs was analyzed by FACS. Cytokine production from CD11c+ pulmonary APCs, and interaction between CD11c+ pulmonary APCs and naïve CD4+ T cells was assessed by ELISA. Ability of antigen presentation by CD11c+ pulmonary APCs was measured by proliferation assay. RESULTS: BSA antigen sensitization during the acute phase of influenza A viral infection induced eosinophil recruitment into the lungs after BSA antigen challenge and moderately increased expression of MHC class II molecules on CD11c+ pulmonary APCs. The interaction between the CD11c+ pulmonary APCs and naïve CD4+ T cells secreted large amounts of IL-10. CONCLUSIONS: BSA antigen sensitization during the acute phase of influenza A viral infection enhanced IL-10 production from naïve CD4+ T cell interaction with CD11c+ pulmonary APCs. The IL-10 secretion evoked Th2 responses in the lungs with downregulation of Th1 responses and was important for the eosinophil recruitment into the lungs after BSA antigen challenge.

Effects of zinc deficient diet on development of atopic dermatitis-like eruptions in DS-Nh mice.

BACKGROUND: Zinc is one of the essential dietary factors and zinc deficiency diminishes the immune system. However, the mechanisms by which zinc deficiency affects the immune system are not fully understood. OBJECTIVE: We analyzed the mechanisms of zinc deficiency affecting the allergic response using a DS-Nh mouse model of atopic dermatitis. METHODS: Male DS-Nh mice were fed a zinc deficient diet for 4 weeks. We measured transepidermal water loss (TEWL) and epidermal moisture level, assessed the skin eruption score, and examined the frequency of lymphocyte subpopulation in spleen and thymus by flow cytometry. The suppressive effect of CD25+CD4+ T cells was analyzed in vitro. The amount of cytokines produced by the spleen cells and the serum IgE levels were measured by ELISA. RESULTS: In DS-Nh mice fed the zinc deficient diet, skin eruptions were exacerbated and serum IgE levels and number of S. aureus on the skin surface was increased. IFN-gamma and IL-13 production by spleen cells was increased. The number of CD25+CD4+ T cells in spleen was significantly decreased, while the percentage of Foxp3 positive cells in the CD25+CD4+ T cells was comparable to those of the controls. CD25+CD4+ T cells from mice fed the zinc deficient diet maintained a suppressive function compared with those from the controls. CONCLUSION: These findings indicate that zinc deficiency influences the skin barrier system and immune system, and suggests that zinc deficiency acts as an exacerbation factor of atopic dermatitis.

Impaired function of dendritic cells in alymphoplasia (aly/aly) mice for expansion of CD25+CD4+ regulatory T cells.

Alymphoplasia (aly/aly) mice are from a naturally occurring strain with a mutation in nuclear factor-kappa B inducing kinase (NIK). The NIK mutation causes disruption of the architecture of the thymus and spleen and aly/aly mice show decreased numbers of CD25+CD4+T cells in the spleen. For the expansion of CD25+CD4+T cells, interactions between dendritic cells (DCs) and CD25+CD4+ regulatory T cells are necessary. We investigated the ability of DCs to induce expansion of CD25+CD4+T cells. We found that DCs are reduced in the spleen of aly/aly mice, and showed low expressions of CD80, CD86 and MHC class II molecules on the surface. DCs from aly/aly mice showed decreased ability to present ovalbumin (OVA) to T cells from OVA specific TCR transgenic mice, and a decreased ability for alloantigen presentation. Further, DCs showed a decreased ability to induce expansion of CD25+CD4+T cells in vitro. Our results suggested that the impairment of DCs in aly/aly mice is responsible, at least in part, for the decreased numbers of CD25+CD4+T cells in the periphery of aly/aly mice.

CpG oligodeoxynucleotides prevent the development of scleroderma-like syndrome in tight-skin mice by stimulating a Th1 immune response.

Tight-skin (Tsk/+) mice develop a disease similar to human scleroderma, characterized by the spontaneous appearance of cutaneous hyperplasia, anti-nuclear antibodies, and emphysema. T helper (Th) 2 cells secreting interleukin (IL)-4 are known to play a critical role in the etiopathogenesis of this disease. Th2-mediated responses can be blocked by treatment with synthetic oligodeoxynucleotides (ODN) containing immunomodulatory CpG motifs. Thus, we examined whether CpG ODN might be of therapeutic benefit in Tsk/+ mice. Administering CpG ODN to Tsk/+ mice every 3 wk starting at 1 wk of age abrogated skin fibrosis. This reduction in skin thickness persisted even after the cessation of therapy, and was accompanied by increased serum levels of IL-12 and an increased ratio of T cells available to secrete interferon-gamma rather than IL-4. CpG ODN therapy also reduced autoantibody production, but did not inhibit the incidence of lung emphysema. Delaying the initiation of CpG ODN treatment until 6 wk of age failed to prevent skin disease. These results indicate that by preferentially promoting the development of a Th1-biased immune milieu in young Tsk/+ mice, CpG ODN can ameliorate Th2-driven scleroderma-like syndrome.

Cyclophosphamide decreases the number, percentage and the function of CD25+ CD4+ regulatory T cells, which suppress induction of contact hypersensitivity.

BACKGROUND: It is well known that cyclophosphamide (Cy) treatment before sensitization paradoxically enhances rather than suppresses contact hypersensitivity (CH) reactions. In fact, Cy-treated mice developed a significant (p < 0.05) increase of the CH reactions to 2,4,6-trinitro-1-chrolobenzene (TNCB) in comparison with untreated mice. OBJECTIVE: In order to examine whether the target cells of Cy in the immuno-augmentative effect are CD25(+) CD4(+) regulatory T cells or not, we investigated effect of Cy treatment on CD25(+) CD4(+) T cells. METHOD: We examined Cy-treated CD25(+) CD4(+) T cells by flow cytometer and by inhibition assay on proliferation of CD25(-) CD4(+) T cells. RESULTS: Cy treatment remarkably reduced the number and percentage of CD25(+) CD4(+) T cells in the spleen and lymph nodes 3 and 5 days later. Moreover, CD25(+) CD4(+) T cells taken from the Cy-treated mice 3 days later showed the lower suppressive activity on proliferation of CD25(-) CD4(+) T cells, as compared to that from the untreated mice. Furthermore, transfer of CD25(+) CD4(+) T cells from untreated mice resulted in a significant decrease (p < 0.05) of the CH reactions enhanced by Cy treatment. CONCLUSION: These results indicate that enhancement of the CH reactions to TNCB by Cy treatment is attributed to the decrease in the number, percentage and the function of CD25(+) CD4(+) regulatory T cells.

Dietary lactosucrose suppresses influenza A (H1N1) virus infection in mice.

This study examined the effects of lactosucrose (4(G)-ß-D-galactosylsucrose) on influenza A virus infections in mice. First, the effects of lactosucrose on fermentation in the cecum and on immune function were investigated. In female BALB/c mice, lactosucrose supplementation for 6 weeks promoted cecal fermentation and increased both secretory IgA (SIgA) levels in feces and total IgA and IgG2a concentrations in serum. Both the percentage of CD4(+) T cells in Peyer's patches and the cytotoxic activity of splenic natural killer (NK) cells increased significantly in response to lactosucrose. Next, we examined the effects of lactosucrose on low-dose influenza A virus infection in mice. After 2 weeks of dietary supplementation with lactosucrose, the mice were infected with low-dose influenza A virus. At 7 days post infection, a comparison with control mice showed that weight loss was suppressed, as were viral titers in the lungs. In the spleens of lactosucrose-fed mice, there was an increase in the percentage of NK cells. Lastly, mice fed lactosucrose were challenged with a lethal dose of influenza A virus. The survival rate of these mice was significantly higher than that of mice fed a control diet. These results suggested that lactosucrose supplementation suppresses influenza A virus infection by augmenting innate immune responses and enhancing cellular and mucosal immunity.

MHC class I-mediated exogenous antigen presentation by exosomes secreted from immature and mature bone marrow derived dendritic cells.

Exosomes are 50-90 nm vesicles with antigen presenting ability carrying major histocompatibility complex (MHC) class I, class II, abundant co-stimulatory molecules and some tetraspan proteins. Although dendritic cells (DCs) are one of the professional antigen presenting cells capable of presenting exogenous antigens in MHC class I-mediated antigen specific manner (cross-presentation), the cross-presentation ability by exosomes from immature or mature DCs are unknown. Here we show that exosomes released from ovalbumin (OVA) protein-pulsed bone marrow derived dendritic cells (BM-DCs) weakly present the peptide determinants to OVA specific MHC class I-restricted CD8(+) T cell hybridomas. The exosomes secreted by OVA(257-264) peptide- or OVA protein-pulsed mature BM-DCs activated OVA specific MHC class I-restricted T cell hybridomas more efficiently than those from immature BM-DCs. Transporters associated with antigen processing (TAP) deficient mice-derived BM-DCs were also used to examine whether functional TAP activity was required for cross-presentation by exosomes. The exosomes obtained from OVA(257-264) peptide-pulsed BM-DCs derived from TAP(-/-) mice showed a significant antigen presenting ability to OVA specific MHC class I-restricted T cell hybridomas. Altogether, our data indicate that BM-DCs secrete exosomes with weak cross-presentation ability.

Predominance of infiltrating IL-4-producing T cells in conjunctiva of patients with allergic conjunctival disease.

PURPOSE: Previous reports have suggested that type 2 cytokine responses at the site of inflammation are important in the pathogenesis of allergic disease. In this study, we investigated the frequency of IFN-gamma- or IL-4-producing T cells from conjunctiva or peripheral blood mononuclear cells (PBMC) from patients with allergic conjunctival diseases. METHODS: We obtained conjunctival samples using Cytobrush and peripheral blood samples from the patients with allergic conjunctival disease. Conjunctival samples and PBMC were stimulated with phorbol myristate acetate and calcium ionophore. Frequencies of cytokine-producing T cells were analyzed by flow cytometry based on the intracellular cytokine staining. RESULTS: The frequency of IL-4-producing conjunctival T cells in patients with vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC) were significantly higher than that in patients with allergic conjunctivitis (AC). The frequencies of IL-4-producing conjunctival CD4+ T cells of the patients with AC, AKC, or VKC were significantly higher than those of peripheral blood CD4+ T cells of the same disease. Further, increased frequency of P-selectin ligand expressing IL-4-producing T cells was observed in conjunctiva compared to that in PBMC of the patients with allergic conjunctival diseases. The frequencies of IL-4-producing peripheral blood T cells in the patients with ACD were significantly higher than that in normal controls. CONCLUSION: These results suggest that IL-4-producing T cells that have infiltrated into the conjunctiva play an important role in the immunopathogenesis of allergic conjunctival diseases, and P-selectin ligand is involved in the entry of T cells into allergic inflammatory site.

IRF8 inhibits C/EBPα activity to restrain mononuclear phagocyte progenitors from differentiating into neutrophils.

Myeloid progenitors lose their potential to generate neutrophils when they adopt the mononuclear phagocyte lineage. The mechanism underlying this lineage restriction remains unknown. We here report that the protein expression of IRF8, an essential transcription factor for the development of dendritic cells (DCs) and monocytes, sharply increases at the monocyte-DC progenitor (MDP) stage and remains high in common monocyte progenitors (cMoPs). Irf8(-/-) MDPs and cMoPs accumulate but fail to efficiently generate their downstream populations, instead giving rise to neutrophils in vivo. IRF8 physically interacts with the transcription factor C/EBPα and prevents its binding to chromatin in MDPs and cMoPs, blocking the ability of C/EBPα to stimulate transcription and neutrophil differentiation. A partial inhibition of C/EBP activity in Irf8(-/-) haematopoietic progenitors alleviates the neutrophil overproduction in vivo. Thus, IRF8 not only bestows monocyte and DC differentiation potential upon mononuclear phagocyte progenitors but also restrains these progenitors from differentiating into neutrophils.

The transcription factor IRF8 counteracts BCR-ABL to rescue dendritic cell development in chronic myelogenous leukemia.

BCR-ABL tyrosine kinase inhibitors (TKI) have dramatically improved therapy for chronic myelogenous leukemia (CML). However, several problems leading to TKI resistance still impede a complete cure of this disease. IFN regulatory factor-8 (IRF8) is a transcription factor essential for the development and functions of immune cells, including dendritic cells. Irf8(-/-) mice develop a CML-like disease and IRF8 expression is downregulated in patients with CML, suggesting that IRF8 is involved in the pathogenesis of CML. In this study, by using a murine CML model, we show that BCR-ABL strongly inhibits a generation of dendritic cells from an early stage of their differentiation in vivo, concomitant with suppression of Irf8 expression. Forced expression of IRF8 overrode BCR-ABL (both wild-type and T315I-mutated) to rescue dendritic cell development in vitro, indicating that the suppression of Irf8 causes dendritic cell deficiency. Gene expression profiling revealed that IRF8 restored the expression of a significant portion of BCR-ABL-dysregulated genes and predicted that BCR-ABL has immune-stimulatory potential. Indeed, IRF8-rescued BCR-ABL-expressing dendritic cells were capable of inducing CTLs more efficiently than control dendritic cells. Altogether, our findings suggest that IRF8 is an attractive target in next-generation therapies for CML.

Shared and distinct functions of the transcription factors IRF4 and IRF8 in myeloid cell development.

Interferon regulatory factor (IRF) 8 and IRF4 are structurally-related, hematopoietic cell-specific transcription factors that cooperatively regulate the differentiation of dendritic cells and B cells. Whilst in myeloid cells IRF8 is known to modulate growth and differentiation, the role of IRF4 is poorly understood. In this study, we show that IRF4 has activities similar to IRF8 in regulating myeloid cell development. The ectopic expression of IRF4 in myeloid progenitor cells in vitro inhibits cell growth, promotes macrophages, but hinders granulocytic cell differentiation. We also show that IRF4 binds to and activates transcription through the IRF-Ets composite sequence (IECS). Furthermore, we demonstrate that Irf8⁻/⁻Irf4⁻/⁻ mice exhibit a more severe chronic myeloid leukemia (CML)-like disease than Irf8⁻/⁻ mice, involving a disproportionate expansion of granulocytes at the expense of monocytes/macrophages. Irf4⁻/⁻ mice, however, display no obvious abnormality in myeloid cell development, presumably because IRF4 is expressed at a much lower level than IRF8 in granulocyte-macrophage progenitors. Our results also suggest that IRF8 and IRF4 have not only common but also specific activities in myeloid cells. Since the expression of both the IRF8 and IRF4 genes is downregulated in CML patients, these results may add to our understanding of CML pathogenesis.

Pre-radiation enhances the cytotoxicity of docetaxel in head and neck squamous cell carcinoma cells.

This study was designed to determine the effect of the treatment schedule on the interaction between docetaxel and irradiation. Human head and neck squamous cell carcinoma (HNSCC) cells with different p53 status, and HSC4 (p53 wild-type) and CAL27 (p53 mutant type) cells were treated with docetaxel and irradiation using three schedules: i) concurrent treatment, ii) docetaxel pretreatment and iii) pre-radiation. Docetaxel and radiation inhibited the proliferation of HSC4 and CAL27 cells in a dose-dependent manner. However, irradiation pretreatment was more effective than the other treatment regimens in all cells. Our data suggest that pre-radiation in HNSCC cells significantly enhances docetaxel cytotoxity by arresting S-phase, and this provides the most effective treatment sequence of docetaxel and radiation combination therapy. Therefore, radiation followed by docetaxel may be the most effective sequence for head and neck cancer therapy.

Human invariant Valpha24+ natural killer T cells acquire regulatory functions by interacting with IL-10-treated dendritic cells.

Glycolipid-reactive Valpha24(+) invariant natural killer T (iNKT) cells have been implicated in regulating a variety of immune responses and in the induction of immunologic tolerance. Activation of iNKT cells requires interaction with professional antigen-presenting cells, such as dendritic cells (DCs). We have investigated the capacity of distinct DC subsets to modulate iNKT cell functions. We demonstrate that tolerogenic DCs (tolDCs), generated by treatment of monocyte-derived DC with interleukin (IL)-10, induced regulatory functions in human iNKT cells. tolDCs, compared with immunogenic DCs, had reduced capacity to induce iNKT-cell proliferation, but these cells produced large amounts of IL-10 and acquired an anergic phenotype. These anergic Valpha24(+) iNKT cells were able to potently inhibit allogeneic CD4(+) T-cell proliferation in vitro. Furthermore, the anergic Valpha24(+) iNKT cells could suppress DC maturation in vitro. We conclude that the interaction of iNKT cells with tolDCs plays an important role in the immune regulatory network, which might be exploited for therapeutic purposes.

Tumor doubling time and local immune response to hepatic metastases from colorectal cancer.

BACKGROUND AND OBJECTIVES: A number of studies have investigated the role of tumor-infiltrating lymphocytes in cancer, yet the local immune response to hepatic colorectal cancer metastasis remains unclear. As the tumor doubling time (DT) of hepatic colorectal cancer metastases is a good index of tumor growth, we examined the correlation between tumor DT and the local immune response by phenotype in hepatic colorectal cancer metastases. METHODS: Tumor DT and local immune response were examined in 20 patients with hepatic colorectal cancer metastases by analyzing tumor-infiltrating lymphocytes using flow cytometry or immunohistochemical studies. Tumor proliferative activity was also investigated by determining the expression levels of Ki-67 and proliferating cell nuclear antigen (PCNA). RESULTS: Locally abundant populations of CD83(+) dendritic cells (DCs) and CD8(+) T cells were positively related to longer tumor DT (P < 0.05), as were abundant CD8(+) T cells having interferon-gamma-producing potentials (P < 0.05). There was no significant correlation between tumor cell expression levels of Ki-67 or PCNA and tumor DT. CONCLUSIONS: Longer DT tumors have increased local populations of CD8(+) T cells and CD83(+) DCs even in hepatic colorectal cancer metastases.