Dendritic cells: their significance in health and disease

Role of antigen-presenting cells in non-ulcerated skin lesions caused by Leishmania (Leishmania) infantum chagasi

In Central America, infection by Leishmania (Leishmania) infantum chagasi causes visceral leishmaniasis and non-ulcerated cutaneous leishmaniasis (NUCL). This work aimed to evaluate the participation of subpopulations of antigen-presenting cells in skin lesions of patients affected by NUCL through double-staining immunohistochemistry using cellular and intracellular markers. Twenty-three skin biopsies from patients affected by NUCL were used. Histological sections stained by HE were used for histopathological study. Immunohistochemical studies were performed using primary antibodies against Langerhans cells, dermal dendritic cells, T lymphocytes, and the cytokines IL-12, IFN-γ, TNF-α, iNOS, and IL-10. The histopathological lesions were characterized by an inflammatory infiltrate, predominantly lymphohistiocytic, of variable intensity, with a diffuse arrangement associated with epithelioid granulomas and discreet parasitism. Double-staining immunohistochemistry showed higher participation of dendritic cells producing the proinflammatory cytokine IL-12 in relation to the other evaluated cytokines. Activation of the cellular immune response was marked by a higher density of CD8 Tc1-lymphocytes followed by CD4 Th1-lymphocytes producing mainly IFN-γ. The data obtained in the present study suggest that antigen-presenting cells play an important role in the in situ immune response through the production of proinflammatory cytokines, directing the cellular immune response preferentially to the Th1 and Tc1 types in NUCL caused by L. (L.) infantum chagasi.

Integrated transcriptomic and quantitative proteomic analysis identifies potential RNA sensors that respond to the Ag85A DNA vaccine

OBJECTIVE

DNA vaccine has emerged as a promising approach with potential for Tuberculosis (TB) prevention in adults. However, the mechanism behind DNA vaccines is still largely unknown.

MATERIALS AND METHODS

Utilizing the CRISPR/Cas9 technique, we engineered Ag85A mutated dendritic cells (Ag85A-M-DCs) in which the Ag85A mRNA derived from Mycobacterium tuberculosis was expressed but not the corresponding protein. Control cells (Ag85A-DCs) expressed both Ag85A mRNA and protein. To better understand the mechanism of antigen presentation following DNA vaccination, integrated transcriptomic and proteomic analysis of dendritic cells (DCs), Ag85A-DCs, and Ag85A-M-DCs were performed.

RESULTS

A total of 723, 278, and 933 differentially expressed genes (DEGs), and 209, 134, and 509 differentially expressed proteins (DEPs) were identified between Ag85A-M-DCs and DCs, Ag85A-DCs and DCs, and Ag85A-M-DCs and Ag85A-DCs, respectively. Integration analysis detected 59, 15, and 64 associated DEGs/DEPs with the same expression trend between Ag85A-M-DCs and DCs, Ag85A-DCs and DCs, and Ag85A-M-DCs and Ag85A-DCs, respectively. KEGG pathway analysis showed that chemokine signaling pathway and MAPK signaling pathway were enriched in all three pairs of comparisons. The protein and protein interaction network revealed that ANXA1 was in the top 10 high-degree hub genes closely related to other genes in all three pairs of comparisons.

CONCLUSION

The results indicated that Ag85A DNA vaccine might transmit immunogenicity information and induce immune responses by activating chemokine signaling pathway and MAPK signaling pathway. ANXA1 may serve as a key target molecule of the Ag85A vaccine with additional potential for TB prevention.

A Quantitative Multivariate Model of Human Dendritic Cell-T Helper Cell Communication

Cell-cell communication involves a large number of molecular signals that function as words of a complex language whose grammar remains mostly unknown. Here, we describe an integrative approach involving (1) protein-level measurement of multiple communication signals coupled to output responses in receiving cells and (2) mathematical modeling to uncover input-output relationships and interactions between signals. Using human dendritic cell (DC)-T helper (Th) cell communication as a model, we measured 36 DC-derived signals and 17 Th cytokines broadly covering Th diversity in 428 observations. We developed a data-driven, computationally validated model capturing 56 already described and 290 potentially novel mechanisms of Th cell specification. By predicting context-dependent behaviors, we demonstrate a new function for IL-12p70 as an inducer of Th17 in an IL-1 signaling context. This work provides a unique resource to decipher the complex combinatorial rules governing DC-Th cell communication and guide their manipulation for vaccine design and immunotherapies.

Inflammation, vitamin D and dendritic cell precursors in chronic kidney disease

Decreased blood dendritic cell precursors (DCP) count is linked with atherosclerotic disease, while reduction of circulating DCP is also seen in patients with chronic kidney disease (CKD). As poor vitamin D status could be linked to a compromised innate immune response, we hypothesized that vitamin D status might be involved in the decrease in circulating DCP in CKD. Moreover, the potential role of inflammation was considered. Circulating myeloid (mDCP), plasmacytoid (pDCP) and total DCP (tDCP) were analysed using flow cytometry in 287 patients with CKD stage 3. Serum 25(OH)D and 1,25(OH)2D levels were measured using enzyme-linked immunosorbent assays (ELISA), interleukin (IL)-6, IL-10 and tumour necrosis factor (TNF)-α using cytometric bead array, C-reactive protein (CRP) using a high-sensitivity (hs) ELISA. Contrary to our hypothesis, there was no association between vitamin D levels and DCP, although their number was decreased significantly in CKD (P < 0·001). Instead, mDCP (r = -0·211) and tDCP (r = -0·188,) were associated slightly negatively with hsCRP but positively with the estimated glomerular filtration rate (eGFR, r = 0·314 for tDCP). According to multivariate linear regression, only higher hsCRP concentration and the presence of diabetes mellitus had a significant negative influence on DCP count (P < 0·03, respectively) but not vitamin D, age and eGFR. A significant impact of vitamin D on the reduction of circulating DCP in CKD 3 patients can be neglected. Instead, inflammation as a common phenomenon in CKD and diabetes mellitus had the main influence on the decrease in DCP. Thus, a potential role for DCP as a sensitive marker of inflammation and cardiovascular risk should be elucidated in future studies.

Skin aging in patients with acquired immunodeficiency syndrome

To evaluate the histomorphometric skin changes over aging patients with autopsied acquired immunodeficiency syndrome (AIDS). In 29 skin fragments of autopsied elderly (older than 50 years) and nonelderly patients with AIDS, epidermal thickness, the number of layers, the diameter of cells, the percentage of collagen and elastic fibers in the dermis, and the number and morphology of Langerhans cells were assessed. Statistical analysis was performed by SigmaStat 2.03 program. The thickness of the epidermis (92.55 × 158.94 μm), the number of layers (7 × 9 layers), and the diameter of the cells (13.27 × 17.6 μm) were statistically lower among the elderly. The quantity of collagen fibers (9.68 × 14.11%) and elastic fibers (11.89 × 15.31%) was also significantly lower in the elderly. There was a decrease in total (10.61 × 12.38 cel/mm(2)) and an increase in immature Langerhans cells (6.31 × 4.98 cel/mm(2)) in elderly patients with AIDS. The aging of the skin of patients with AIDS is amended in different histomorphometric aspects, the epidermis constituents suffer less pronounced changes in normal aging, and the dermis has more intense changes in elastic fibers and collagen.

Role of abnormal Langerhans cells in oral epithelial dysplasia and oral squamous cell carcinoma: A pilot study

BACKGROUND

The oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC), although initiated by tobacco carcinogens, their progression is due to inability of Langerhans cells (LCs) to detect these abnormal cells and promote lymphocytes to destroy these cells. We assessed and quantified the tumor associated LCs and inflammation in OED and OSCC to understand their role.

MATERIALS AND METHODS

Fifty-five microscopic sections were assessed (27 OED and 28 OSCC). The LCs were detected using S-100 immunohistochemical marker. The number of tumor associated LCs were counted. The presence of abnormal appearing large cells and its relation to histopathologic grade and inflammation was assessed.

RESULTS

Significant increase in the LC count was observed in OSCC when compared to dysplasia. Large, abnormal appearing cells were observed in dysplasia and carcinomas however, these were more pronounced in moderate dysplasia and poorly-differentiated carcinomas. The presence of these abnormal appearing cells was associated with decrease in lymphocytic infiltrate.

CONCLUSION

The present study indicates more LC are recruited into the carcinoma. These accumulated nonfunctional LC in the tumor tissue are indicative of aggressive tumor with potential malignant transformation.

Update on the challenges and recent advances in cancer immunotherapy

This overview provides an analysis of some of the immunotherapies currently in use and under investigation, with a special focus on the tumor microenvironment, which we believe is a major factor responsible for the general failure of immunotherapy to date. It is our expectation that combining immunotherapy with methods of altering the tumor microenvironment and targeting regulatory T cells and myeloid cells will yield favorable results.

Detection and isolation of dendritic cells using Lewis X-functionalized magnetic nanoparticles

dendritic cell (DC)-specific intracellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) is a receptor found on DCs that recognizes antigens bearing mannose-rich or fucosylated glycans, including Lewis X (Le(X)). Here, we report the fabrication of magnetic nanoparticles coated with multivalent Le(X) glycans using Cu (I)-catalyzed azide-alkyne cycloaddition. The resulting nanoparticles are selective and biocompatible, serving as a highly efficient tool for DC detection and enrichment.

Immunomodulating activity of Nymphaea rubra Roxb. extracts: activation of rat dendritic cells and improvement of the T(H)1 immune response

Polysaccharides play a key role in enhancing immune function and facilitating cellular communication. Here, we purified Nymphaea rubra Roxb. polysaccharides (NR-PS) by treating them with pullulanase. They were then cultured with immature dendritic cells (DCs) derived from rat bone marrow hematopoietic cells (BMHCs). After treatment with bioactive NR-PS with a degree of polymerization (DP) value of 359.8, we found that the DCs underwent morphological changes indicative of activation. CD80/86 (87.16% ± 8.49%) and MHC class II (52.01% ± 10.11%) expression levels were significantly up-regulated by this treatment compared to the controls (65.45% ± 0.97% and 34.87% ± 1.96%). In parallel, endocytosis was also reduced (167.94% ± 60.59%) after treatment with 25 μg/mL of NR-PS as measured by the medium fluorescence intensity compared to the control (261.67% ± 47.26%). Furthermore, the DCs after treatment with 25 μg/mL NR-PS showed increased IL-12 (102.09 ± 10.16 to 258.78 ± 25.26 pg/mL) and IFN-γ (11.76 ± 0.11 to 15.51 ± 1.66 pg/mL) secretion together with reduced IL-10 secretion (30.75 ± 3.35 to 15.37 ± 2.35 pg/mL), which indicates a T_H1 immune response. In conclusion, NR-PS exhibits stimulatory effects on rat DCs and promotes the secretion of T_H1 cytokines. Taken together, our studies are the first to show that NR-PS is an immunomodulator affecting the maturation and functioning of DCs.

Composition analysis and immuno-modulatory effect of okra (Abelmoschus esculentus L.) extract

The aim of this study was to analyse the composition of okra (Abelmoschus esculentus L.) extract and investigate the effect of A. esculentus L. polysaccharides (AE-PS) on the maturation and function of dendritic cells (DCs) derived from rat bone marrow hematopoietic cells (BMHCs) in vitro. BMHC-derived immature DCs (BMHC-imDCs) were extracted from rats and treated with AE-PS. The hydrolysed okra extract contained 0.6% β-1, 3-D-glucan. AE-PS induced the presence of polymorphic nuclei and elongated protrusion in the BHMC-imDCs, indicating DC activation. Treatment with 100 μg/mL of AE-PS increased the MHC class II and CD80/86 expression levels by 41% and 42%, respectively. Treated cells had reduced endocytosis activity. The secretion of IL-12 and IFN-γ increased significantly by 120% and 75%, respectively, when treated with 100 μg/mL of AE-PS. Moreover, IL-10 production was reduced by 66%. In conclusion, AE-PS exhibits stimulatory effects on rat dendritic cells and promotes the secretion of T(H)1 cytokines.

Enumeration of human peripheral blood dendritic cells throughout the life

Human aging is associated with immunosenescence, a process characterized by alterations in numerical and functional features of immune system components. Dendritic cells (DCs) are the main antigen-presenting cells, playing a pivotal role in adaptive and innate immunity. Therefore, we investigated the distribution of human circulating DCs throughout the life, in order to contribute to the knowledge of the physiological background underlying the aging of immune system. Cytofluorimetric analysis of peripheral blood samples by all-aged healthy population showed a significant decrease of circulating DCs and of their two main subsets among age. This reduction was limited to the plasmacytoid cell subtype when young and old subjects were analyzed separately. The analysis of circulating Treg cell number in a cohort of the subjects showed a significant reduction with increasing age and a positive significant correlation to myeloid or plasmacytoid absolute numbers. In conclusion, this work provides a large set of data of normal reference values of peripheral blood dendritic cells in healthy population suitable for comparative clinical studies concerning pathological immune dysfunctions.

Zoledronic acid modulates maturation of human monocyte-derived dendritic cells

Zoledronic acid (ZA) is a drug of the bisphosphonate class, which is widely used for the treatment of both osteoporosis and skeletal metastasis. Besides its main bone antiresorptive activity, ZA displays antitumor properties, by triggering the expansion and activation of γδ T-cells, which exert an antitumor effect through dendritic cells (DCs). Several studies have reported the interaction between ZA and γδ T-cells, but the potential immunoregulatory activity of this drug on DCs has scarcely been investigated. Therefore, in this paper, we evaluated the effects of a therapeutic dose of ZA on the in vitro generation and maturation of DCs derived from peripheral blood monocytes of healthy adult donors. We demonstrate that ZA treatment did not affect DC differentiation, but inhibited DC maturation on lipopolysaccharide activation, as shown by the impaired expression of maturation surface markers and reduced ability to induce allogeneic T-cell proliferation. Interestingly, IL-10 secretion by mature DCs was significantly lower in ZA-treated cells than in controls. We conclude that ZA exerts its immunological in vitro activity also by modulating the maturation of DCs.

Immunohistochemical staining of Langerhans cells in HPV-positive and HPV-negative cases of oral squamous cells carcinoma

The Human Papillomavirus (HPV) has been strongly implicated in development of some cases of oral squamous cell carcinoma (OSCC). However, the immunological system somehow reacts against the presence of this virus. Among the cells involved in such mechanism of defense Langerhans cells (LC) stand out, which are responsible for processing and presenting antigens.

The effect of cigarette smoking on cervical langerhans cells and T and B lymphocytes in normal uterine cervix epithelium

The objective of our study was to evaluate the effect of smoking on intraepithelial Langerhans cells and T and B lymphocytes in normal cervical epithelium. A total of 47 women who underwent hysterectomies because of uterine leiomyomata were investigated. Thirty-two individuals were nonsmokers and 15 were current smokers. A segment of tissue was taken from the cervix after the removal of the uterus and was formalin-fixed and paraffin-embedded for histologic analysis. The identification of the Langerhans cells and T and B lymphocytes was carried out by immunohistochemical analysis. The number of intraepithelial Langerhans cells was expressed by the amount of cells per square millimeter of epithelium. For T and B lymphocytes, a score expressed the cell count. The comparison of the number of intraepithelial Langerhans cells between smoking and nonsmoking women showed a significant difference (P=0.045), but it did not occur in relation to the number of T and B cells between the 2 groups. There was also no significant difference in relation to the number of cigarettes smoked per day, time of consumption, and total amount of cigarettes smoked throughout the lifetime. It was shown that smoking reduces the number of intraepithelial Langerhans cells in a normal cervix but does not influence the number of T and B lymphocytes.

Immunohistochemical evaluation of the inflammatory response in periodontal disease

In order to contribute to the knowledge of the pathogenesis of periodontal disease, an immunohistochemical analysis of the density of inflammatory mononucleated cells and the number of dendritic cells was performed using anti-CD4, anti-CD20, anti-CD25, anti-CD68 and anti-protein S-100 antibodies in 17 cases of chronic gingivitis (CG) and 25 of chronic periodontitis (CP). The CD4+ and CD68+ cells exhibited a diffuse distribution in the connective tissue. CD20+ cell distribution was predominantly in groups and the CD25+ cells exhibited a diffuse or focal distribution. The S-100+ cells were identified in the epithelium and the lamina propria, exhibiting distinct morphology and number. The statistical analysis showed no significant differences (p>0.05) between CG and CP regarding the density of the CD4+ and CD20+ cells and the number of S-100+ cells. However, significant differences (p<0.05) were found between the groups in the density of CD25+ and CD68+ cells . The density of macrophages was greater in CG and the level of cellular activation of the lymphocyte infiltrate was greater in CP. No differences were detected between the aforementioned conditions regarding the density of the T and B lymphocytes and to the number of the dendritic cells.

The impact of comorbid atopic disease on asthma: clinical expression and treatment

Clinically, asthma and allergic rhinitis involve separate regions of the respiratory tract while representing a common underlying inflammatory syndrome. Much evidence supports an epidemiologic association between the diseases, paranasal sinus involvement in both conditions, and parallel relationship in severity and treatment outcomes. Pathophysiologic mechanisms, including immunoglobulin E (IgE)- mediated inflammation, are also shared. Blocking IgE with the recombinant humanized monoclonal antibody omalizumab demonstrated clinical efficacy in patients with upper and lower airway diseases. IgE blockade, leukotriene modulation, and B-cell depletion therapy have all exhibited success in chronic inflammation, reinforcing and expanding the beneficial role of immunomodulation of global mediators.

Langerhans Cells in Cervical Intraepithelial Neoplasia Related to Smoking Habits

OBJECTIVE

Compare the numerical densities of intraepithelial Langerhans cells of uterine cervix of women affected by cervical intraepithelial neoplasia grade 3 (CIN 3) with their smoking habits.

MATERIALS AND METHODS

A total of 71 conization specimens of women affected by CIN 3 were separated in 3 groups according to their smoking habits (smokers, nonsmokers, and former smokers). The identification of the Langerhans cells was performed by immunohistochemical analysis using antibodies to S100 protein. The number of intraepithelial Langerhans cells was counted at x400 magnification under a light microscope, and a 10-field count was performed in areas of CIN 3 of each section. Results were expressed as number of cells per square millimeter of epithelium.

RESULTS

There was no significant difference in the number of Langerhans cells per square millimeter of epithelium in areas affected by CIN 3 among the 3 groups (p = .5). There was also no significant difference in the number of cigarettes smoked per day (p = .09), duration of consumption (p = .34), total amount of cigarettes smoked during the whole life (p = .18), and duration of abstention (p = .2).

CONCLUSIONS

It was not shown that smoking reduces the number of intraepithelial Langerhans cells in the cervix of women affected by CIN 3.

The potential of exosomes in immunotherapy

In 1996, B cell-derived exosome immunogenicity was first reported. In 1998, dendritic cell-derived exosomes were also shown to have immunogenic properties in mice, leading to tumour eradication. These observations showed for the first time that exosomes were bioactive vesicles with immuno-regulatory roles and potent antitumour effects. Exosomes are secreted vesicles formed in late endocytic compartments (multivesicular bodies). Vesicles exocytosed from multivesicular bodies into the extracellular medium are referred to as 'exosomes' and should not be confused with the more recently described 'ribonuclease complex' also named exosome. Exosomes are vesicles of 50-100 nm in diameter, formed by inward budding of the endosomal membrane in a process that sequesters particular proteins and lipids. This review will describe the biogenesis, the protein and lipid compositions, and the biological functions of exosomes; this review will also present their immunostimulatory functions in mice and humans, and will discuss their possible use as cancer vaccines.

Poor in vitro maturation and pro-inflammatory cytokine response of dendritic cells in children at genetic risk of type 1 diabetes

Type 1 diabetes (T1D) has been associated with an aberrant maturation of dendritic cells (DC). We studied the maturation of monocyte-derived DC in children with newly diagnosed T1D and in healthy children with genetic risk for T1D. Peripheral blood monocytes from children with newly diagnosed T1D (n = 12; mean age 13.2 years), children with human leukocyte antigen (HLA)-risk genotype of T1D (n = 7; mean age 12.7 years) and healthy children (n = 14; mean age 11.2 years) were in vitro differentiated into DC. Expression of HLA-DR, CD80/86 and CD11c and secretion of interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, IL-6 and IL-10 were measured using flow cytometry. Lower percentage of DC expressed CD11c and HLA-DR, and decreased production of TNF-alpha was found in children with newly diagnosed T1D and in children at genetic risk when compared to healthy children. Children with risk genotype also had decreased IL-12 production by DC. Children with T1D and children at genetic risk of T1D appear to have similar aberrancies in the maturation of DC, which may predispose to beta-cell autoimmunity.

The dendritic cell-derived protein DC-STAMP is highly conserved and localizes to the endoplasmic reticulum

Recently, we described the molecular identification of dendritic cell-specific TrAnsMembrane protein (DC-STAMP), a multimembrane-spanning protein preferentially expressed by human DC (hDC). In this report, we describe the identification and expression profile of the murine homologue of DC-STAMP (mDC-STAMP) as well as the characterization of the DC-STAMP protein. The results demonstrate that mDC-STAMP is over 90% homologous to hDC-STAMP and is also preferentially expressed by DC in vitro and ex vivo. mDC-STAMP expression is enhanced by interleukin-4 and down-regulated upon DC maturation. Analysis of differently tagged DC-STAMP proteins further demonstrates that hDC-STAMP and mDC-STAMP are glycosylated and primarily localize to an intracellular compartment. Applying confocal microscopy and electron microscopy, we demonstrate that hDC-STAMP localizes to the endoplasmic reticulum (ER) in human embryonic kidney 293 cells as well as hDC transduced with an adenovirus encoding hDC-STAMP-green fluorescent protein fusion protein. These data imply that DC-STAMP may exert its effect in the ER.

Correlation of c-erbB-2 and S-100 expression with the malignancy grading and anatomical site in oral squamous cell carcinoma

An immunohistochemical analysis of 32 cases of oral squamous cell carcinoma (eight in the inferior lip, eight in the lateral angle of the tongue, eight in the palate and eight in the mouth floor) was performed to evaluate the expression pattern of c-erbB-2 protein and S-100-positive cells in the lesions. The immunohistochemical expression was correlated with the tumour anatomical site and histological grading of malignancy. A higher frequency of c-erbB-2-positive cases was found in the tongue, even though no correlation could be detected between the protein expression and the tumour histological grading. With respect to the S-100-positive cells, it was observed that a quantitative decrease was present in the cases classified as high-grade tumours when compared to the low ones (P = 0.0007). Thus, c-erbB-2 immunohistochemical expression is correlated with anatomical localization, and the expression of the S-100 Langerhans' cell markers is decreased significantly in high-grade carcinomas.

Evaluation of Myeloid and Lymphoid Dendritic Cells in Peritoneal Fluid in Women with Non-malignant Ovarian Tumors

PROBLEM

Identification of myeloid and lymphoid dendritic cells (DCs) in peritoneal fluid (PF) and peripheral blood (PB) of patients with ovarian pathology.

METHOD OF STUDY

PF and PB were collected from 60 patients who underwent laparoscopy because of non-malignant ovarian tumors. Mononuclear cells were separated by gradient centrifugation. The cell surface antigens were determined by flow cytometry using monoclonal antibodies.

RESULTS

Both myeloid and lymphoid DCs were detected in PF and PB of women with ovarian tumors. The percentage of myeloid DCs was significantly higher in PF than in PB. The concentration of PF myeloid DCs was the highest (P < 0.05) in patients with dermoid cysts (0.67 x 10(6)/mL PF) in comparison with the other studied groups, excluding patients with normal pelvis.

CONCLUSIONS

Domination of myeloid and not lymphoid cells in PF may support the hypothesis that local PF immune disturbances may play a role in some non-malignant ovarian pathology.

Dendritic cell-based immunotherapy for the treatment of hematological malignancies

Dendritic cells (DCs) are professional antigen-presenting cells and are frequently used in current immunotherapy protocols. The administration of DCs loaded with tumor-associated proteins or peptides results in the induction of immune responses against different types of malignant cells. Methods for large-scale generation of DCs in a sufficient quality and quantity have permitted their use in clinical experiments. DC-based vaccines have already shown promise in follicular non-Hodgkin's lymphoma, and to some extent, in other hematological malignancies. Several strategies have been developed to boost their potency as a new and relatively non-toxic treatment modality. Our review focuses on clinical trials using DCs in the treatment of hematologic malignancies and on recent studies of the immunophenotype, development, and maturation of DCs may have an important impact on designing DC-based antitumor vaccines.

The novel differentiation of human blood mononuclear cells into CD1a-negative dendritic cells is stimulated in the absence of exogenous cytokines by an extract prepared from pinecones

The production of dendritic cells, both in-vivo and in-vitro, has become the intense focus of research activities. Common to many of these production protocols is the use of cytokines, typically granulocyte-monocyte colony stimulating factor and either interleukin 4 or tumor necrosis factor alpha or a combination of all three. Herein, we report our findings that a proprietary pinecone extract is capable of in a dose-dependent manner, and in the absence of exogenous cytokines, the rapid differentiation from peripheral blood mononuclear cells of mature CD1a-negative dendritic cells.

The biogenesis and functions of exosomes

Exosomes are membrane vesicles with a diameter of 40-100 nm that are secreted by many cell types into the extracellular milieu. They correspond to the internal vesicles of an endosomal compartment, the multivesicular body and are released upon exocytic fusion of this organelle with the plasma membrane. Intracellularly, they are formed by inward budding of the endosomal membrane in a process that sequesters particular proteins and lipids. The unique composition of exosomes may confer specific functions on them upon secretion. Although their physiological role in vivo is far from being unraveled, it is apparent that they function in a multitude of processes, including intercellular communication during the immune response. Exosomes may have evolved early in the evolution of multicellular organisms and also seem to be important for tissue developmental processes.

Microglia in diseases of the central nervous system

Microglia (MG) are enigmatic cells of the central nervous system (CNS). MG are morphologically, antigenically and functionally flexible, and have the potential for mobility and proliferation. MG are professional antigen-presenting cells and constitute part of the local CNS innate immune system, communicating with other immune cells via chemokines, cytokines and growth factors. MG contain several antigenic and functional markers similar to macrophages and dendritic cells (DCs), but also present several differences from DCs. The exact role(s) played by MG in the normal human CNS is the topic of lively debate. MG participate in many reactive processes in the CNS and are therefore an integral part of lesions in a variety of pathologic conditions. It is thought that MG may exacerbate diverse neurological conditions, including viral encephalitis, AIDS, Multiple Sclerosis (MS) and Alzheimer's disease. A recurrent theme is the perpetuation by MG of pathological cycles of monocyte recruitment, activation and cytopathic secretions, and/or auto antigen presentation.