Metachromatic cells in nasal mucosa after allergen challenge

Metachromatic cells in the nasal mucosa were studied in relation to symptoms in 16 schoolchildren and 11 adults with hay fever who were challenged with pollen outside the pollen season, using either a gentle scraping-cytocentrifugation method for collection of mucosal specimens or biopsies. There was a temporary redistribution of metachromatic cells towards the mucosal surface appearing 5-24 h after challenge, with a correlation between the quantity of metachromatic cells and symptom scores. Thus, a single exposure to high doses of allergen may contribute to priming in susceptible individuals.     

Recruitment of dendritic cells in oral lichen planus

Using immunohistochemistry the presence of different dendritic cell (DC) subsets was analysed in 16 biopsies from patients with oral lichen planus (OLP). A significant increase of CD1a+/Langerin+ Langerhans cells, DC-SIGN+ DC and CD123+/BDCA2+ plasmacytoid DCs (PDCs) was found in the epithelium and in the stroma of OLP biopsies compared to normal oral mucosa. A proportion of DCs were mature DC-LAMP+ and expressed S100 or CD11c, typically found in the interdigitating DCs of nodal T-cell areas. Double staining revealed that mature DCs co-expressed CCR7, thus indicating the development of a nodal migratory phenotype upon maturation. Significant recruitment of PDCs producing IFN-alpha was demonstrated by the expression of MxA within the lichenoid inflammatory infiltrate and close cell-to-cell contacts between PDCs and mature DCs were observed, with a significant correlation between the numbers of these two populations. Moreover, PDCs were also found to contain Granzyme-B, an associated-cytotoxic granule protein, inducing target cell apoptosis. Taken together, these results suggest that PDCs may promote maturation of DCs and amplify the cytotoxicity of lymphoid cells. Finally, the recruitment of different subtypes of DC, such as Langerhans cells, stromal DC-SIGN+ DCs and PDCs, associated with a significant proportion of mature DCs, acquiring a CCR7+ 'migratory' phenotype, indicate that they may play a pivotal role in the development of the lichenoid inflammatory infiltrate that occurs typically in OLP.     

Identification of three distinct subsets of migrating dendritic cells from oral mucosa within the regional lymph nodes

To investigate the phenotypic and migrational properties of oral mucosal dendritic cells (OMDCs), fluorescein isothiocyanate (FITC) was painted onto mouse buccal mucosa and the expression patterns of functional molecules in FITC-bearing migrating DCs within the regional lymph nodes (RLNs) were analysed. We found three distinct subpopulations of migrating OMDCs within the RLNs: CD11c^hi CD207⁻ (F1), CD11c^int/lo CD207⁻ (F2) and CD11c^int/lo CD207⁺ (F3). The F1 DCs reached the RLNs earlier (after 24 hr) but diminished immediately. Additionally, F1 DCs expressed high levels of CD11b. The F2 DCs migrated continuously to the RLNs and maintained the highest ratio of all three fractions. The F3 DCs migrated slowly to the RLNs and demonstrated a late peak at 96 hr. In addition, F3 DCs showed the highest CD205 expression levels of all three subsets. All fractions of migrating OMDCs expressed CD80, CD86 and major histocompatibility complex class II at high levels, suggesting that all OMDCs are in a mature stage and have the potential for antigen presentation. All migrating OMDCs lacked CD8α expression. Taken together, our results indicate that the lack of CD207 is one factor that identifies submucosal DCs. Both F1 and F2 DCs lack CD207; F1 DCs are resident and F2 DCs are newly recruited following FITC application. The F3 DCs, which express CD207, are mucosal Langerhans cells that migrate later. The identification of OMDC subsets should facilitate further studies investigating the functional roles of each fraction.     

Counter regulation of the high affinity IgE receptor, FcεRI, on human airway dendritic cells by IL-4 and IL-10

Background:  Immunoglobulin E is a signalling molecule within the environment of the respiratory tract, the high affinity receptor for which, FcεRI, is expressed by dendritic cells (DC). Little is known, however, of the expression and function of FcεRI on DC in the human respiratory tract.
Methods:  CD1c⁺ DC were purified from surgically resected nasal turbinates of 11 atopic and 12 nonatopic patients with chronic rhinosinusitis. Expression of FcεRI was determined by flow cytometry. Cytokine production by DC was determined by cytometric bead array.
Results:  Expression of FcεRI was significantly elevated on respiratory tract dendritic cells (RTDC) from atopic as compared to nonatopic patients. Activation of RTDC through FcεRI induced production of the pro-inflammatory cytokines IL-6 and TNF-α, and the anti-inflammatory cytokine IL-10. The production of IL-6 and TNF-α was elevated in atopic compared to nonatopic patients studied. Conversely IL-10 production was elevated in nonatopic patients. Concomitant activation of FcεRI and stimulation of RTDC with IL-4 inhibited production of IL-10 by RTDC. Neutralization experiments with anti-IL-10 Ab enhanced whereas addition of exogenous IL-10 to RTDC inhibited FcεRI-mediated inflammatory cytokine production.
Conclusion:  The function of FcεRI on RTDC from patients with rhinosinusitis is susceptible to counter regulation by IL-4 and IL-10.     

The immunotherapeutic potential of dendritic cells in type 1 diabetes

Type 1 diabetes is an autoimmune disease characterized by destruction of the pancreatic islet beta cells that is mediated primarily by T cells specific for beta cell antigens. Insulin administration prolongs the life of affected individuals, but often fails to prevent the serious complications that decrease quality of life and result in significant morbidity and mortality. Thus, new strategies for the prevention and treatment of this disease are warranted. Given the important role of dendritic cells (DCs) in the establishment of peripheral T cell tolerance, DC‐based strategies are a rational and exciting avenue of exploration. DCs employ a diverse arsenal to maintain tolerance, including the induction of T cell deletion or anergy and the generation and expansion of regulatory T cell populations. Here we review DC‐based immunotherapeutic approaches to type 1 diabetes, most of which have been employed in non‐obese diabetic (NOD) mice or other murine models of the disease. These strategies include administration of in vitro‐generated DCs, deliberate exposure of DCs to antigens before transfer and the targeting of antigens to DCs in vivo. Although remarkable results have often been obtained in these model systems, the challenge now is to translate DC‐based immunotherapeutic strategies to humans, while at the same time minimizing the potential for global immunosuppression or exacerbation of autoimmune responses. In this review, we have devoted considerable attention to antigen‐specific DC‐based approaches, as results from murine models suggest that they have the potential to result in regulatory T cell populations capable of both preventing and reversing type 1 diabetes.     

食管黏膜树突状细胞表型分析

目的:研究食管黏膜树突状细胞(DCs)表型特点。方法:内镜下收集健康人食管黏膜标本,Ficoll-Hypaque密度梯度离心法分离食管黏膜标本中的单个核细胞,采用磁珠分选技术分离DCs,流式细胞仪分析食管黏膜DCs表型。结果:健康人食管黏膜含3类单个核细胞:HLA-DRhigh/CD13low,HLA-DRmed/CD13+和HLA-DR-/CD13+;HLA-DRhigh/CD13low细胞表达不同DCs亚群表面标志,是食管黏膜DCs;健康人食管黏膜DCsCD80、CD83、CD86表达水平低,是不成熟DCs。结论:成功分离了食管黏膜DCs,证实HLA-DRhigh/CD13low细胞是食管黏膜DCs。     

Intravenous immunoglobulin and dendritic cells

Intravenous immunoglobulin (IVIg) has increasingly been used for the treatment of autoimmune and systemic inflammatory diseases, and in supportive therapy of immunodeficient patients. Available clinical and experimental evidence suggests, however, that a wide spectrum of immune-mediated conditions could benefit from IVIg, including acute and chronic/relapsing diseases and autoimmune diseases mediated by pathogenic autoantibodies or by autoaggressive T-cells. Dendritic cells (DCs) are professional antigen-presenting cells and because of their capacity to stimulate nave T-cells, they play a central role in the initiation of primary immune responses. Several immunomodulatory agents have been shown to inhibit DC activation. Recently, we examined the effects of IVIg on differentiation, maturation, and functions of DCs. We demonstrate that DCs are one of the targets for the immunomodulatory effects of IVIg.     

Constitutive mRNA and immunoreactivity for IL-2 in human nasal mucosa

Background The nasal mucosa is the initial site in the upper airway of host defence against antigenic challenge in the form of airborne allergens, irritants, toxins and infectious agents, and yet little is known about nasal mucosal cytokine expression and function. We hypothesized that IL-2 might play a role in immunocompetence of the upper airway. Methods IL-2 immunoreactivity was measured by ELISA in nasal secretions and by Western blot. Immunohistochemistry and electron microscopy were performed on turbinated tissue. mRNA for IL-2 was evaluated by RTPCR and Southern hybridization. Results IL-2 immunoreactivity was demonstrated by Western blot and quantitated by an enzyme immunoassay. Immunohistochemical and electron microscopy analysis of turbinate tissue revealed interstitial staining for IL-2. By RTPCR, IL-2 message was evident in 5/5 atopies and 5/5 non-atopics. IL-2 message was expressed in all subjects by Southern hybridization to an internal probe after PCR. Conclusion This study has demonstrated constitutive expression of IL-2 protein and mRNA in the upper airway of heallhy individuals. The further characterization of cytokines in the upper airway could provide useful insights into immune regulation at the mucosal level.     

Cancer immunotherapy using RNA-loaded dendritic cells

Dendritic cells (DC) are the most professional antigen-presenting cells of the immune system and are capable of initiating immune responses in vitro and in vivo. One of the great challenges in immunotherapy protocols is to introduce relevant antigens into DC for stimulation of major histocompatibility complex (MHC) class I- and class II-restricted anti-tumour or anti-viral immunity. This review will focus on the development of mRNA-loaded DC-based immunotherapy vaccines. First, several published results concerning mRNA transfection efficiency in DC are compared. Next, an overview is given for several published studies describing CD8+ and CD4+ T-cell clone activation using RNA-loaded DC. These data show that RNA-loaded DC efficiently process and present antigenic epitopes. Next, published data from in vitro T-cell activation studies using RNA-loaded DC are summarized and provide evidence that RNA-loaded DC can efficiently stimulate in vitro primary and secondary immune responses. Finally, the summarized data provide evidence that RNA-loaded DC are a promising strategy for the development of future cancer vaccination strategies.     

Forkhead box P3+ T cells express interleukin-17 in nasal mucosa of patients with both allergic rhinitis and polyposis

The pathogenesis of nasal polyposis remains unclear; it severely affects patients' quality of life and complicates inflammation in adjacent organs such as sinusitis and asthma. Aberrant immune regulatory function in these patients is proposed. The present study aims to examine the regulatory T cells (T(reg) ) in nasal mucosa of patients with allergic rhinitis (AR) and nasal polyposis (NP). Patients with AR or AR/NP were treated with inferior turbinectomy for their inferior turbinate hyperplasia. Surgically removed nasal mucosa was collected to examine the T(reg) by immunohistochemistry and flow cytometry. The results showed that more forkhead box P3 (FoxP3)(+) cells were found in AR with polyps than in those with AR alone. Further studies revealed that these FoxP3(+) T cells from AR/NP group also expressed interleukin (IL)-17. In vitro study showed that staphylococcal enterotoxin B (SEB) induced CD4(+) FoxP3(+) T cells to become FoxP3(+) IL-17(+) cells via facilitating the expression of IL-6, that in synergy with transforming growth factor-beta, induce the expression of IL-17 in FoxP3(+) cells. We conclude that FoxP3(+) IL-17(+) T cells were localized in the nasal mucosa of patients with AR and NP. SEB may play a role in converting FoxP3(+) T(reg) to FoxP3(+) IL-17(+) T cells. The presence of IL-17(+) FoxP3(+) T cells may play a role in the remodelling of the nasal airways in certain people who develop polyps, irrespective of whether or not they are atopic.     

Potential applications of dendritic cells

Dendritic cells (DCs) are the professional antigen‐presenting cells of the immune system. Following infection or inflammation they undergo a complex process of maturation, and migrate to lymph nodes where they present antigens to T cells. Their decisive role in inducing immunity formed the rationale for DC immunotherapy: DCs loaded with tumor antigens are injected into cancer patients to stimulate T cells to eradicate tumors. Effective immune responses and favourable clinical outcomes have indeed been observed, but only in a minority of patients. For effective immunotherapy DCs need to traffic throughout the vascular and lymphatic system to reach the T‐cells located within lymph nodes. Though most immunotherapeutic agents are administered intravenously, DCs are predominantly administered intradermally. We observed that < 5% of intradermally administered mature DCs reach the draining lymph nodes amounting to inefficient homing. Despite this low number we could measure effective immune responses in some patients, but generally this may be too low. We demonstrated that DC maturation is a prerequisite to exert their immunostimulatory capacity in vivo. Immuno‐monitoring revealed a remarkable difference in immune responses. In patients vaccinated with immature DC the KLH responses as well as DTH reactivity against KLH and tumor‐peptides were weak and absent, respectively. In contrast, in patients vaccinated with mature DC a pronounced T cell as well a B cell response (IgG) against KLH were observed. Analysis of the response against the tumor peptides demonstrated little or no reactivity in blood. However, following intradermal administration of a delayed type hypersensitivity (DTH) challenge with gp100‐ and tyrosinase‐peptide loaded DC essentially all patients vaccinated with mature DC showed a positive induration. Moreover, we showed the predictive value of the presence or absence of antigen‐specific T cells in biopsies from DTH sites. In clinically responding patients, T cells specific for the antigen preferentially accumulated in the DTH site in accordance with the applied antigen in the DTH challenge.     

CD-1 (T6), HLA-DR-expressing cells, presumably Langerhans cells, in nasal mucosa

In the skin, epidermal Langerhans cells (LC) constitute a major population of antigen-presenting cells. These cells are characterized by the expression of both CD-1 (T6) and HLA-DR on the cell membrane. We wanted to know whether similar CD-1/HLA-DR-positive cells occur in the nasal mucosa of patients with an isolated grass pollen allergy and in non-allergic controls. CD-1/HLA-DR-positive dendritic cells were found in columnar and cuboidal epithelium and the lamina propria of the nasal mucosa. These CD-1/HLA-DR-positive cells presumably correspond with LC in the skin. We also found significantly more CD-1-positive cells in nasal biopsy samples of allergic than in those of the non-allergic controls. In the allergic patients some of the CD-1-positive cells were found to be surface IgE-positive, possibly due to passive adherence of IgE to Fc receptors.     

Antigen presenting cells in the nasal mucosa of patients with allergic rhinitis during allergen provocation

Background The role of antigen presenting cells (APC) in allergic rhinitis is underexposed. Allergen presentation to T lymphocytes is probably an important aspect of the pathophysiological mechanism of allergic rhinitis. Objectives The aim of the study was to investigate the presence and dynamics of APC with special emphasis on Langcrhans cells (LC) in the nasal mucosa of patients with an isolated grass pollen allergy during an out-of-season 2-week allergen exposure, mimicking the natural grass pollen season. Methods Seventeen patients with isolated grass pollen allergy and four control subjects were challenged daily with allergen during a 2-week period in the winter. Biopsy specimens were obtained once before, six times during and once after the provocation period. Biopsy sections were stained with monoclonal antibodies: OKT6 (CDla-Langerhans cells). Ki-M6 (CD68 macrophages), L25 (dendritic cells), anti-IgE, HLA-DR and HLA-DQ (Major Histoeompatibihty Complex Class II - antigen presenting eells), as well as staining with acid phosphatase. Results APC with different characteristics are present in the epithelium and lamina propria of the nasal mucosa. The number of LC increased significantly in epithelium and lamina propria. IgE⁺-LC were present in the nasal mucosa and increase during provocation, HLA-DR⁺ cells with dendritic and lymphocytic morphology and HLA-DQ⁺ cells were found. The number of these cells increased during provocation in epithelium and lamina propria. The number of HLA-DR⁺ epithelial cells did not change. A significant increase in the number of Ki-M6⁺ cells (macrophages) was found in the lamina propria. However, Ki-M6⁺ cells increased to the same extent in the lamina propria in the control group. Conclusion APC are influenced by allergen provocation. This study supports the hypothesis that (IgE⁺) LC are involved in allergic rhinitis. The role macrophages play remains doubtful.     

Taming cancer by inducing immunity via dendritic cells

Summary: Immunotherapy seeks to mobilize a patient's immune system for therapeutic benefit. It can be passive, i.e. transfer of immune effector cells (T cells) or proteins (antibodies), or active, i.e. vaccination. In cancer, passive immunotherapy can lead to some objective clinical responses, thus demonstrating that the immune system can reject tumors. However, passive immunotherapy is not expected to yield long-lived memory T cells that might control tumor outgrowth. Active immunotherapy with dendritic cell (DC)-based vaccines has the potential to induce both tumor-specific effector and memory T cells. Early clinical trials testing vaccination with ex vivo -generated DCs pulsed with tumor antigens provide a proof-of-principle that therapeutic immunity can be elicited. Yet, there is a need to improve their efficacy. The next generation of DC vaccines is expected to generate large numbers of high-avidity effector CD8⁺ T cells and to overcome regulatory T cells. Therapeutic vaccination protocols will combine improved ex vivo DC vaccines with therapies that offset the suppressive environment established by tumors.     

Purified human oral mucosal Langerhans cells function as accessory cells in vitro.

Oral mucosal Langerhans cells (OMLC) may have an important role in the induction of immune responses to oral pathogens. In this study, anti-HLA-DR antibody-coated immunomagnetic beads were used to purify OMLC from suspensions of normal human buccal epithelium and the capacity of the purified cells to function as accessory cells (AC) was investigated. Electron microscopy was used to show that the purified cells possessed all recognized ultrastructural features previously described in epidermal Langerhans cells. Using T lymphocyte proliferation assays in hanging drop microcultures, it was found that purified OMLC could function as AC for responses to concanavalin A by autologous T cells. Purification of OMLC from small biopsies of oral mucosa has enabled us to show that OMLC, like epidermal Langerhans cells, can function as AC in vitro.