Proliferation in monocyte-derived dendritic cell cultures is caused by progenitor cells capable of myeloid differentiation

Dendritic cells (DC) can be generated by culture of adherent peripheral blood (PB) cells in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). There is controversy as to whether these DC arise from proliferating precursors or simply from differentiation of monocytes. DC were generated from myeloid-enriched PB non-T cells or sorted monocytes. DC generated from either population functioned as potent antigen-presenting cells. Uptake of [H-3]-thymidine was observed in DC cultured from myeloid-enriched non-T cells. Addition of lipopolysaccharide or tumor necrosis factor-alpha led to maturation of the DC, but did not inhibit proliferation. Ki67(+) cells were observed in cytospins of these DC, and by double staining were CD3(-)CD19(-)CD11c(-)CD40(-) and myeloperoxidase(+), suggesting that they were myeloid progenitor cells. Analysis of the starting population by flow cytometry demonstrated small numbers of CD34(+)CD33(-)CD14(-) progenitor cells, and numerous granulocyte-macrophage colony-forming units were generated in standard assays. Thus, production of DC in vitro from adherent PB cells also enriches for progenitor cells that are capable of proliferation after exposure to GM-CSF. Of clinical importance, the yield of DC derived in the presence of GM-CSF and IL-4 cannot be expanded beyond the number of starting monocytes. (C) 1998 by The American Society of Hematology.

Increase of gingival matured dendritic cells number in elderly patients with chronic periodontitis

Objective: The purpose of this study was to evaluate the inflammatory cell subset proportions in the upper gingival connective tissue, including mature dendritic cells (DC) in elderly and younger patients with generalized chronic periodontitis in order to further understand the effect of aging on gingival inflammatory phenomenon. Methods: Gingival tissue specimens presenting chronic periodontitis from 8 elderly patients aged >75 (test group, group T) and from 8 younger patients aged 50-60 (considered as controls, group C) were analysed by immunohistochemistry using monoclonal antibodies against CD45RB, CD4, CD8, CD19, CD68, DC-SIGN, DC-LAMP molecules. The number of each immunolabelled cells subset was counted using image analysis. Results: The difference in the number of CD45RB + leucocytes in the upper gingival connective tissue between groups was not significant permitting to use it as reference. As compared. to group C, the lymphocyte subsets/CD45RB + leucocytes ratios tended to decrease in group T but the decrease was significant only for CD4 + T lymphocytes/ CD45RB + cells ratio (p < 0.03). On the opposite, the ratios of antigen-presenting cells DC-SIGN + cells/CD45RB + cells and DC-LAMP + cells/CD45RB + cells were significantly increased;(p < 0.03 and <0.0001, respectively) in group T. Moreover, in group T the DC-LAMP + cells/DC-SIGN + cells ratio was significantly increased (p < 0.05) showing an increased number of matured dendritic cells. Conclusion: During chronic periodontitis in elderly patients, our results show a decrease in the ratio of gingival CD4 + lymphocyte subset associated with an increase in the ratios of antigen-presenting cells subsets and more particularly maturated DC-LAMP + dendritic cells. (C) 2008 Elsevier Ltd. All rights reserved.

Impact of photodynamic therapy on inflammatory cells during human chronic periodontitis

The aim of this study was to evaluate the effects of the photodynamic therapy (PDT) on the inflammatory infiltrate and on the collagen network organization in human advanced chronic periodontitis Two different drug delivery systems (DDS) were tested (liposomes and nanoemulsions) to determine if the effects of PDT could differ according to the DDS used Sixteen patients presenting two teeth with chronic advanced periodontitis and Important tooth mobility with clinical indication of extraction were included in the group liposomes (group L n = 8) or in the group nanoemulsions (group N n = 8) in order to compare the effects of each DDS Seven days before extractions one tooth of each patient was treated with PDT using phthalocyanine derivatives as photosensitizers and the contralateral tooth was taken as control In group L the density of gingival collagen fibers (66 +/- 19%) was significantly Increased (p < 0 02) when compared to controls (35 +/- 21%) Concerning the antigen-presenting cells PDT had differential effects depending on the drug delivery system the number of macrophages was significantly decreased (p < 0 05) in group L while the number of Langerhans cells was significantly decreased in group N (p < 0 02) These findings demonstrate that PDT presents an impact on gingival Inflammatory phenomenon during chronic periodontitis and leads to a specific decrease of antigen-presenting cells populations according to the drug delivery system used (C) 2010 Elsevier B V All rights reserved

Could endogenous self-peptides presented by dendritic cells initiate rheumatoid arthritis?

The critical interaction initiating and perhaps perpetuating rheumatoid arthritis (RA) is the presentation of arthritogenic antigen to autoreactive T cells. In contrast to many organ-specific autoimmune diseases, no candidate autoantigens have yet been confirmed for RA. Here, Ranjeny Thomas and Peter Lipsky examine the role of dendritic cells in autoimmune disease, leading to the hypothesis that activation of T cells by endogenous self-peptides may be sufficient to initiate RA.

Major histocompatibility complex (MHC) class II-positive dendritic cells in the rat iris - In situ development from MHC class II-negative precursors

Purpose. To examine the postnatal development of major histocompatibility complex (MHC) class II-positive dendritic cells (DC) in the iris of the normal rat eye. Methods. Single-and double-color immunomorphologic studies were performed on whole mounts prepared from rat iris taken at selected postnatal ages (2 to 3 days to 78 weeks). Immunopositive cells were enumerated, using a quantitative light microscope, and MHC class II expression on individual cells was assessed by microdensitometric analysis. Results. Major histocompatibility class II-positive DCs in the iris developed in an age-dependent manner and reached adult-equivalent density and structure at approximately 10 weeks of age, considerably later than previously described in other DC populations in the rat. In contrast, the anti-rat DC monoclonal antibody OX62 revealed a population of cells present at adult-equivalent levels as early as 3 weeks after birth. Dual-color immunostaining and microdensitometric analysis demonstrated that during postnatal growth, development of the network of MHC class II-positive DCs was a consequence of the progressive increase in expression of MHC class II antigen by OX62-positive cells. Conclusions. During postnatal growth, the DC population of the iris develops initially as an OX62-positive-MHC class II-negative population, which then develops increasing MHC class II expression in situ and finally resembles classic DC populations in other tissue sites. Maturation of the iris DC population is temporally delayed compared with time to maturation in other tissue sites in the rat.

CD1a and Factor XIIIa Immunohistochemistry in Leprosy: A Possible Role of Dendritic Cells in the Pathogenesis of Mycobacterium leprae Infection

Leprosy is a curable chronic granulomatous infectious disease caused by the bacillus Mycobacterium leprae. This organism has a high affinity for skin and peripheral nerve cells. In the evolution of infections, the immune status of patients determines the disease expression. Dendritic cells are antigen-presenting cells that phagocytose particles and microorganisms. In skin, dendritic cells are represented by epidermal Langerhans cells and dermal dendrocytes, which can be identified by expression of CD1a and factor XIIIa (FXIIIa). In the present study, 29 skin samples from patients with tuberculoid (13 biopsies) and lepromatous (16 biopsies) leprosy were analyzed by immunohistochemistry using antibodies to CD1a and FXIIIa. Quantitative analysis of labeling pattern showed a clear predominance of dendritic cells in tuberculoid leprosy. Difference between the number of positive cells of immunohistochemistry for the CD1a and FXIIIa staining observed in this study indicates a role for dendritic cells in the cutaneous response to leprosy. Dendritic cells may be a determinant of the course and clinical expression of the disease.

Specific infiltration of langerin-positive dendritic cells in EBV-infected tonsil, Hodgkin lymphoma and nasopharyngeal carcinoma

We report here the existence of a novel subset of langerin (CD207)-positive, immature dendritic cells (DCs) (CD83(neg)) abundantly infiltrating Epstein Barr virus (EBV)-infected areas in tonsil, Hodgkin lymphoma and nasopharyngeal carcinoma. These CD207(+) DCs differ from conventional epidermal Langerhans cells in their lack of CD1a and CCR6 and their unusual tissue localization. CD207(+) DC infiltration strongly correlates with EBV infection because it was neither detected in EBV negative specimens nor in tissues infected with other human viruses. These immature DCs might represent good candidates for induction of the EBV-specific immune response.

Broadsheet - Dendritic cells and their emerging clinical applications

Dendritic cells (DC) are now recognised as a unique leukocyte type, consisting of two or more subsets. The origins and functional inter-relationships of these cells are the subject of intense basic scientific investigation. They play important roles in initiating and directing immune responses, defending the host from pathogens and maintaining self tolerance. Fundamental studies are defining new molecules and mechanisms associated with DC function. The first methods for counting these rare blood cell populations are already providing interesting new clinical data. Indeed, abnormal DC function may contribute to deficiencies in the immune response against malignancies. Phase I trial data suggests that DC-based cancer vaccination protocols may contribute an important new biological approach to cancer therapy. Manipulation of DC to facilitate allogeneic transplantation and even to manage autoimmune disease are likely developments.

HIV gp120 receptors on human dendritic cells

Dendritic cells (DCs) are important targets for human immunodeficiency virus (HIV) because of their roles during transmission and also maintenance of immune competence. Furthermore, DCs are a key cell in the development of HIV vaccines. In both these settings the mechanism of binding of the HIV envelope protein gp120 to DCs is of importance. Recently a single C-type lectin receptor (CLR), DC-SIGN, has been reported to be the predominant receptor on monocyte-derived DCs (MD-DCs) rather than CD4. In this study a novel biotinylated gp120 assay was used to determine whether CLR or CD4 were predominant receptors on MDDCs and ex vivo blood DCs. CLR bound more than 80% of gp120 on MDDCs, with residual binding attributable to CD4, reconfirming that CLRs were the major receptors for gp120 on MDDCs. However, in contrast to recent reports, gp120 binding to at least 3 CLRs was observed: DC-SIGN, mannose receptor, and unidentified trypsin resistant CLR(s). In marked contrast, freshly isolated and cultured CD11c(+ve) and CD11c(-ve) blood DCs only bound gp120 via CD4. In view of these marked differences between MDDCs and blood DCs, HIV capture by DCs and transfer mechanisms to T cells as well as potential antigenic processing pathways will need to be determined for each DC phenotype. (Blood. 2001;98:2482-2488) (C) 2001 by The American Society of Hematology.

Antigen-presenting cells in human periodontal disease tissues

T cells are present in the inflammatory infiltrates of periodontal disease lesions and require antigen presentation by antigen-presenting cells (APCs). While it is still not known whether Th1 or Th2 cells predominate in these lesions, it has been reported that different APCs may induce activation of different T-cell subsets. An immunoperoxidase technique was used to investigate the presence of CD1a+, CMRF-44+, CMRF-58+ and CD83+ dendritic cells, CD14+ macrophages or dendritic cell precursors and CD19+ B cells in gingival biopsies from 21 healthy or gingivitis and 25 periodontitis subjects. The samples were divided into three groups according to the size of infiltrate (group 1, small infiltrates; group 2, medium infiltrates; group 3, extensive infiltrates). The presence of numerous CD1a+ Langerhans cells was noted in the epithelium with no differences between the healthy/gingivitis and periodontitis groups. The percentage of CD83+ dendritic cells in the infiltrates was higher than the percentage of CD1a+, CMRF-44+ or CMRF-58+ dendritic cells. Endothelial cells positive for CD83 were found predominantly in areas adjacent to infiltrating cells, CD83+ dendritic cells being noted in the region of CD83+ endothelium. The percentage of CD14+ cells in the inflammatory infiltrates was similar to that of CD83+ dendritic cells. B cells were the predominant APC in group 2 and 3 tissues. The percentage of B cells in group 3 periodontitis lesions was increased in comparison with group 1 periodontitis tissues and also in comparison with group 3 healthy/gingivitis sections. Functional studies are required to determine the roles of different APC subpopulations in periodontal disease.

Monitoring and isolation of blood dendritic cells from apheresis products in healthy individuals: a platform for cancer immunotherapy

The fundamental role of dendritic cells (DC in initiating and directing the primary immune response is well established. Furthermore, it is now accepted that DC may be useful in new vaccination strategies for preventing certain malignant and infectious diseases. As blood DC (BDC physiology differs from that of the DC homologues generated in vitro from monocyte precursors, it is becoming more relevant to consider BDC for therapeutic interventions. Until recently, protocols for the isolation of BDC were laborious and inefficient; therefore, their use for investigative cancer immunotherapy is not widespread. In this study, we carefully documented BDC counts, yields and subsets during apheresis (Cobe Spectra), the initial and essential procedure in creating a BDC isolation platform for cancer immunotherapy. We established that an automated software package (Version 6,0 AutoPBPC) provides an operator-independent reliable source of motionuclear cells (MNC for BDC preparation. Further, we observed that BDC might be recovered in high yields, often greater than 100% relative to the number of circulating BDC predicted by blood volume. An average of 66 million (range, 17-179) BDC per 10-1 procedure were obtained, largely satisfying the needs for immunization. Higher yields were possible on total processed blood volumes of 151. BDC were not activated by the isolation procedure and, more importantly, both BDC subsets (CD11c(+)CD123(low) and CD11c(-)CD123(high)) were equally represented. Finally, we established that the apheresis product could be used for antibody-based BDC immunoselection and demonstrated that fully functional BDC can be obtained by this procedure. (C) 2002 Published by Elsevier Science B.V.

Mast cells and oral inflammation

Mast cells are mobile granule-containing secretory cells that are distributed preferentially about the microvascular endothelium in oral mucosa and dental pulp. The enzyme profile of mast cells in oral tissues resembles that of skin, with most mast cells expressing the serine proteases tryptase and chymase. Mast cells in oral tissues contain the pro-inflammatory cytokine tumour necrosis factor-alpha in their granules, and release of this promotes leukocyte infiltration during evolving inflammation in several conditions, including lichen planus, gingivitis, pulpitis, and periapical inflammation, through induction of endothelial-leukocyte adhesion molecules. Mast cell synthesis and release of other mediators exerts potent immunoregulatory effects on other cell types, while several T-lymphocyte-derived cytokines influence mast cell migration and mediator release. Mast cell proteases may contribute to alterations in basement membranes in inflammation in the oral cavity, such as the disruptions that allow cytotoxic lymphocytes to enter the epithelium in oral lichen planus. A close relationship exists among mast cells, neural elements, and laminin, and this explains the preferential distribution of mast cells in tissues. Mast cells are responsive to neuropeptides and, through their interaction with neural elements, form a neural immune network with Langerhans cells in mucosal tissues. This facilitates mast cell degranulation in response to a range of immunological and non-immunological stimuli. Because mast cells play a pivotal role in inflammation, therapies that target mast cell functions could have value in the treatment of chronic inflammatory disorders in the oral cavity.

Factors determining the spontaneous activation of splenic dendritic cells in culture.

Dendritic cells (DCs) serve as a link between the innate and adaptive immune systems. The activation state of DCs is crucial in this role. However, when DCs are isolated from lymphoid tissues, purified and placed in culture they undergo 'spontaneous' activation. The basis of this was explored, using up-regulation of DC surface MHC II, CD40, CD80 and CD86 as indicators of DC activation. No evidence was found for DC damage during isolation or for microbial products causing the activation. The culture activation of spleen DCs differed from that of Langerhans cells when released from E-cadherin-mediated adhesions, since E-cadherin was not detected and activation still occurred with β-catenin null DCs. Much of the activation could be attributed to DC-DC interactions. Although increases in surface MHC II levels occurred under all culture conditions tested, the increase in expression of CD40, CD80 and CD86 was much less under culture conditions where such interactions were minimised. DC-to-DC contact under the artificial conditions of high DC concentration in culture induced the production of soluble factors and these, in turn, induced the up-regulation of co-stimulatory molecules on the DC surface.

Notch1 deficiency dissociates the intrathymic development of dendritic cells and T cells.

Thymic dendritic cells (DCs) form a discrete subset of bone marrow (BM)-derived cells, the function of which is to mediate negative selection of autoreactive thymocytes. The developmental origin of thymic DCs remains controversial. Although cell transfer studies support a model in which T cells and thymic DCs develop from the same intrathymic pluripotential precursor, it remains possible that these two types of cells develop from independent intrathymic precursors. Notch proteins are cell surface receptors involved in the regulation of cell fate specification. We have recently reported that T cell development in inducible Notch1-deficient mice is severely impaired at an early stage, before the expression of T cell lineage markers. To investigate whether development of thymic DCs also depends on Notch1, we have constructed mixed BM chimeric mice. We report here that thymic DC development from Notch1(-/)- BM precursors is absolutely normal (in terms of absolute number and phenotype) in this competitive situation, despite the absence of Notch1(-/)- T cells. Furthermore, we find that peripheral DCs and Langerhans cells are also not affected by Notch1 deficiency. Our results demonstrate that the development of DCs is totally independent of Notch1 function, and strongly suggest a dissociation between intrathymic T cell and DC precursors.