摘要:

A family of dendritic cells has been identifiedin situandin vitroby microscopy and immunolabeling. The members of this family include the dendritic cells isolated from lymphoid organs, Langerhans cells [LC] of the epidermis, veiled cells in afferent lymph, and interdigitating cells [IDC]in the T-cell areas. Some common features to all members of the family are high levels of MHC class II antigens, a lack of most B and T cell markers, and an absence or low levels of macrophage/granulocyte antigens. This review summarizes the markers of mouse dendritic cells as assessed by a panel of monoclonal antibodies, and stresses a few recent findings. 1) In spleen, there are two populations of dendritic cells. More than 75% of isolated cells are 33D1+, NLDC145−, and JI1d−, while the remainder have the reciprocal phenotype and thus share the NLDC145 antigen of IDC. Thymic dendritic cells, released by collagenase digestion, and epidermal LC also are 33DI−, NLDC145+, J11d+. 2) When epidermal LC are placed in culture, there are changes in cell function and phenotype. There is a decrease in Fc-γreceptors and the F4/80 macrophage antigen, an increase in class I and II MHC products and p55 IL-2 receptors, and persistence of the NLDC145 IDC antigen. The cultured LC thereby resembles the IDC. 3) A new antibody N418 shows that dendritic cells express the p150/90 member of the leukocyteβ2integrin family. Immunolabeling of tissue sections of spleen indicates that N418+dendritic cells not only are present in the periarterial sheaths, the location of IDC, but also in“nests”at the periphery of the T area where 33D1 has been found. The peripheral collections interrupt the marginal zone of macrophages that separates white and red pulp, and places the dendritic cells in the path of T cells as they move through the white pulp. Therefore the members of the dendritic cell family have important markers in common, as well as differences that are associated with state of immunologic function and location.

ISSN:0883-0185    

DOI:10.3109/08830189009056621

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Dendritic cells from human blood and synovial exudates are distinct from other leukocytes and are homogeneous by several criteria. Morphologically, their most prominent feature is numerous veils. Phenotypically, dendritic cells lack the surface antigens that identify monocytes, T cells, B cells, and NK cells. Human dendritic cells strongly express class I and class II MHC products, and have a distinct array of integrin and adhesin molecules. In many systems, dendritic cells are potent stimulators of T cell function. In the allogeneic mixed leukocyte reaction, for example, dendritic cells are 30–100 times more efficient than other cells in presenting transplantation antigens, for the induction of DNA synthesis, cytokine release, and generation of cytotoxic T cells. In addition, dendritic cells can induce the long-term clonal growth of T lymphocytes. Although dendritic cells are a minor subpopulation in human blood, new isolation protocols are available that permit efficient isolation and enrichment to>90%.

ISSN:0883-0185    

DOI:10.3109/08830189009056622

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The thymus is the primary organ in which T cells undergo rearrangement of T cell receptorαandβgenes, positive selection for affinity to self MHC products, and elimination (negative selection) of reactivity to self antigens. These events require an interaction of the developing T cell with other cell types in the thymus. The latter include epithelial cells, macrophages, dendritic cells, and the recently described thymic B cells the majority of which are CD5+. Here we review the identification and isolation of thymic dendritic cells and CD5+B cells. We consider phenotype, ontogeny, and function, including possible contributions to the induction of self tolerance. Thymic dendritic cells are similar to spleen dendritic cells, but are larger and exhibit a few differences in phenotype. Dendritic cells from both organs are equally potent accessory cells for the MLR and lectin-induced, T cell proliferation. Thymic dendritic cells have higher levels of Fc receptors and support anti-CD3 dependent mitogenesis. Thymic CD5+B cells share phenotypic features with peritoneal CD5+B cells. However thymic B cells neither proliferate nor form antibody producing cells in response to the stimulation with LPS or anti-IgM plus IL-4, but do respond to stimulation with MHC class II-restricted helper T cells. Thymic dendritic cells and CD5+B cells both appear at a similar time in ontogeny, about 14 d of gestation, which is the time T cell differentiation begins to take place. Dendritic cells from spleen, which are potent activators for peripheral T cells, are also potent inactivators for thymic-derived cytotoxic T cells. A correlation between reactivity to MIs products and the expression of TCR-Vβgenes is well documented, and B cells are the primary APC for this antigen. Therefore, thymic CD5+B cells may be a good tool for the investigation of tolerance to Mls products.

ISSN:0883-0185    

DOI:10.3109/08830189009056623

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Interstitial dendritic cells (IDC) were first identified in the interstitium of non-lymphoid organs as leucocytes which stained intensely with anti-MHC class II antibodies. These cells have been identified in several species including man, and can be distinguished from tissue macrophages by their immunological phenotype and cytochemical and functional characteristics. IDC appear to be closely related to lymphoid dendritic cells (DC), and have the capacity to bind antigen and stimulate T lymphocyte responses. It seems probable that they represent a stage of non-lymphoid dendritic cell differentiation necessary for antigen surveillance, similar to the Langerhans cell of the skin. Exposure to antigen appears to induce migration of these cells into adjacent lymphatics and subsequent localization in the interfollicular areas of lymph node, where the DC present processed antigen to activate a primary T cell response. The IDC has been identified as the passenger leucocyte within organ allografts which contributes substantially to graft immunogenicity, so that eradication of donor organ IDC improves organ graft survival.

ISSN:0883-0185    

DOI:10.3109/08830189009056624

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Studies from several laboratories on lung tissue samples from human and experimental animals have identified la+cells with characteristic pleiomorphic (dendritic) morphology in the epithelium and underlying connective tissue, in both the conducting airways and in the distal lung. These dendritic cells (DC) are particularly prominent within the airway epithelium, forming a contiguous network equivalent to the Langerhans cells network of the epidermis. They may be readily concentrated from enzymatically disrupted respiratory tract tissue samples on the basis of their physical properties (notably non-adherence, lack of Fc-receptors and ultra-low density on percoll), and function as highly effective antigen presenting cellsin vitro. Evidence is also accumulating that respiratory tract DC populations respond dynamically to local tissue inflammation, and as such may play a prominent role in immunoinflammatory disease processes in the airways and the distal lung.

ISSN:0883-0185    

DOI:10.3109/08830189009056625

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Dendritic cells (DC) are a family of bone marrow-derived MHC class II expressing cells which occur in small numbers in most lymphoid and nonlymphoid tissues. They represent a distinct lineage of leukocytes which can be found in two distinct maturational stages:immature dendritic cellsare exemplified by the Langerhans cells in the epidermis, and are considered to be precursors to themature dendritic cellsin the lymphoid organs. These maturational stages can be distinguished by phenotypic and functional characteristics. Immature dendritic cells are weak stimulators of resting T lymphocytes but are excellent in processing soluble protein antigens for presentation to T cell clones. Mature dendritic cells show exactly reciprocal features. In this review the relatively few available data on cytokine production by DC and responses of DC to cytokines are collected. Our goal is to consider the role of cytokines in DC function including the transition from immature to mature stages.

ISSN:0883-0185    

DOI:10.3109/08830189009056626

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Dendritic cells (DC) from human peripheral blood are susceptible to productive and probably to latent infection with HIV-I [18, 29]. Infection of DC also occursin vivosince in HIV-seropositive individuals Langerhans’cells of the skin [16] and DC from peripheral blood ([17], in preparation) are infected. In peripheral blood 3–25% of DC, identified as large, low-density cells lacking monocyte markers, are infected as judged byin situhybridization with an HIV probe. This contrasts with the lower proportion (<0.2%) of other cells infected. DC exposed to HIVin vitroorin vivofail to present other antigens or mitogens to stimulate T cells [29, 38, 41]. This functional defect in infected DC is not blocked by the presence of soluble CD4 antigen and occurs in the absence of T cell infection suggesting a block at the level of the antigen-presenting cell itself. Infection, depletion and dysfunction of DC in HIV seropositive patients is already present in asymptomatic individuals and this precedes the appearance of T cell defects. We speculate that loss of functional DC may be a fundamental defect leading to a block in recruitment of resting T cells into immune responses.In contrast to the HIV-induced impairment of antigen presentation by DC, these cells were potent stimulators of responses to the HIV antigens themselves. Normal DC infected with HIVin vitrostimulated primary proliferative and cytotoxic T cell responses ([52], in preparation). These were produced in cells from individuals expressing a range of different MHC types but the cytotoxic cells, once produced, killed autologous but not allogeneic, infected T cell blasts. Primary response to viral peptides can also be produced suggesting that this system may be useful for identifying immunogenic epitopes of HIV using cells from sero-negative, non-immunocompromised individuals.

ISSN:0883-0185    

DOI:10.3109/08830189009056627

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

We review the phenotypic and functional properties of sheep afferent lymph dendritic cells. These dendritic cells bear surface immunoglobulin and can acquire antigen/antibody complexes, bothin vitroandin vivo. Our data suggest a role for Fc receptors in the capture of antigen by these cells. Dendritic cells collected afterin vivoantigen pulsing are capable of stimulating T cell proliferation in an antigen-specific manner. Afferent dendritic cells express all the known groups of presentational molecules involved in activation of T cells, namely MHC class I and class II, and CD1. These results suggest a role for afferent dendritic cells in the activation ofαβandγδT cells.

ISSN:0883-0185    

DOI:10.3109/08830189009056628

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Interdigitating (IDC) cells of the thymus have been characterizedin situby their ultrastructure and phenotype. Thymic dendritic cells (DC), thought to represent theirin vitrocorrelate, resemble splenic DC in their ability to initiate peripheral T cell responses.In vivo, however, DC of the thymus have been implicated in tolerance induction, although at one time they were thought to impart MHC-restriction on developing T cells. Our present understanding of these areas is reviewed here.Anin vitromodel has been developed to address directly the function of DC in the thymus. Mature DC and immature thymocytes migrate into deoxyguanosine-treated thymus lobes where they adopt a reciprocal distribution, DC homing primarily to the medulla while the thymocytes remain in the cortex. These observations support the close relationship between thymic DC and IDC and provide a powerful tool to examine the role of DC in thymocyte ontogeny.

ISSN:0883-0185    

DOI:10.3109/08830189009056629

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The biology of antigen presenting cells (APC) traditionally is studied in tissue culture systems using T cells that have been expanded beforehand by stimulation with antigen. Here we consider the distinctive roles of dendritic cells for sensitizing or priming T cells bothin vitroandin vivo. Several functions of dendritic cells have been identified in tissue culture that are pertinent to T cell sensitization. These include the ability to a) capture and retain foreign antigens in an immunogenic form, b) bind antigen-specific resting lymphocytes, and c) activate T cells to produce lymphokines and undergo long term clonal growth. Dendritic cells have several propertiesin vivothat also would contribute to APC function. These are a) their widespread tissue distribution permitting access to antigens in most organs, b) the capacity to home via the blood stream and afferent lymph to the T-dependent areas of spleen and lymph node, and c) the ability to capture antigen in antigen-pulsed animals. Dendritic cells bearing antigen have been administeredin situto initiate responses like contact sensitivity, graft rejection, and antibody formation. A most striking recent example is that, when dendritic cells are pulsed with protein antigensin vitroand administered to immunologically naive mice, there is direct priming of antigen-specific T cells that are restricted to the MHC of the injected APC.

ISSN:0883-0185    

DOI:10.3109/08830189009056630

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor