Showing papers in "Seminars in Immunology in 1999"

TL;DR: In this review the nature and function of individual cell types are discussed and the current knowledge regarding the parameters governing their entry into the CNS is examined.

TL;DR: M cells can be considered as pathogen translocators toward immunocompetent areas of the gut, thus opening the possibility to harness this property in order to design new mucosal vaccines or vaccine vectors.

TL;DR: Structural observations of M cells and of intestinal lymphoid tissues stimulated functional, structural and molecular biologic investigations which now provide the basis for many of the current concepts of mucosal immunology and the roles of M Cells in initiation of defensive immune responses.

TL;DR: Experiments showing that developing T cells crosstalk to different thymic epithelial cells in a stepwise fashion guarantee normal thymopoiesis are reviewed.

TL;DR: The importance of factors in afferent lymph, the specific distribution of extracellular matrix proteins, potential soluble regulators of cell traffic, and evidence for an active role of lymphatic endothelial cells in the regulation of lymphocyte traffic are discussed.

TL;DR: The molecular features of M cell apical surfaces that promote adherence and transport are crucial for understanding the strategies that pathogens use to exploit this pathway.

TL;DR: This work proposes a model in which specific signals are required to initiate Th2 differentiation, but that this pathway can be inhibited following a strong TCR stimulus.

TL;DR: B lymphocyte antigen receptors, mannose receptors and receptors for the Fc region of immunoglobulins, promote both internalization and efficient presentation at low antigen concentrations, and binding to specific membrane receptors concentrate antigens on antigen presenting cells and mediates efficient uptake.

TL;DR: The present review examines rheumatoid arthritis and transplantation rejection as two examples of pathological conditions where chemokine directed leukocyte infiltration aids in the pathogenesis of the disease.

TL;DR: Investigations supporting an obligatory role for the IL-7 receptor pathway in early T cell development are reviewed, and future directions in this field are suggested to reveal whether and how signals initiated by the cytokine receptors and pre-TCR may intersect, and to define which down-stream molecular events are regulated by these receptors.

TL;DR: It is concluded that, in principle, the concepts of mucosal immune protection can be applied to these sites of MALT, however, it is questionable whether a separate cell type similar to intestinal M cells exists and performs antigen sampling in the different MALT epithelia.

TL;DR: This work has shown that thymic stromal cell architecture phenotype is found in autoimmune diseases suggesting that abnormalities in the establishment of medullary microenvironments might be linked to the development of autoimmunity.

TL;DR: The number of class I MHC/peptide complexes on the surface of antigen presenting cells crucially influences the activation of T cells and this influences the recognition by MHC class I-restricted T cells.

TL;DR: Fetal Thymus Organ Culture provides an experimental system where interactions within the normal three-dimensional architecture of the thymusin vivowhich are critical for normal development to proceed, and where appropriate is compared to the use of dispersed culture systems.

TL;DR: The current status of knowledge with regard to early developmental stages in the human thymus is reviewed and recent data on later developmental stages, in particular concerning positive selection and maturation of T cells are discussed.

TL;DR: The thymic development of CD4(+) T cells incorporates the opposing processes of positive and negative selection to produce mature lymphocytes which respond to foreign peptides in the context of self-major histocompatibility complex class II molecules into a model in which these events occur in two temporally and anatomically distinct steps.

TL;DR: Rapid selection of fitting H/L chain pairs, forming BCR on the surface, allows B-lineage cells to enter the mature B cell pool where the rearrangement machinery is shut off, securing allelic exclusion of L chain loci in most B cells.

TL;DR: The development of MALT, FAE and probably M cells is a multistep process that requires signalling pathways common to all secondary lymphoid tissues, but also MALT-specific factors.

TL;DR: This review compares the signals that thymocytes may receive from the pre T cell receptor (preTCR) with signalling from TCRgammadelta, and suggests that these signals may determine, co-determine, facilitate, or cement the alphabeta/g Mohammadelta lineage decision, in concert with signals from additional molecules, such as Notch and cytokine receptors.

TL;DR: Single-chain antibodies specific for evolutionarily conserved epitopes, shared by human and mouse, are isolated and used in murine thymic functional assays, providing an experimental approach to functional analysis of the human thymus.

TL;DR: A review of results derived from different experimental strategies to ex- amine the contributions of the PTKs and the adaptor molecules to pre-TCR and TCR signaling processes concludes that these families of kinases coordinate their actions to promote signaling.

TL;DR: Allelic exclusion of the alpha and beta chains of the T cell receptor is maintained by different mechanisms as discussed by the authors, such as successful rearrangement of only one of the two beta-chain loci.

TL;DR: The implications of recent experimental attempts to address beta-selection, as well as how pre-TCR activation is linked to the changes in gene expression that underlie thymocyte development are discussed.

TL;DR: In this article, a modification of the local environment, such as occurs during contact of the epithelium with lymphoid cells or microorganisms, plays a key role in this process.

TL;DR: Depending on the nature of the antigen (soluble or infectious), there may be different sites of antigen entry through the intestine, and each site may have distinct efficiency to promote a protective immune response, depending on the presence and function of dendritic cells.

TL;DR: The plasticity of the immune system relies on stochastic, i.e. random, decisions as well as on controlled events.

TL;DR: Various intracellular pathways that are activated after TCR engagement are outlined in this review, and their contribution to thymocyte selection is discussed.

TL;DR: Current evidence suggests that two populations of thymic emigrants with distinct tissue-homing specificities to spleen and lymph node contribute to the development of the foetal peripheral T cell pool.

TL;DR: The lymphocyte subsets in blood and various tissues in normal and virus-infected individuals prior to and following drug treatment are compared and an absence of selective CD4(+) cell decreases or increases is indicated, highlighting the importance of lymphocyte trafficking and compartmentalization in regulating blood T cell levels and suggesting a reevaluation of the currently favoured paradigm.

TL;DR: Through this quality control of peptide loading, DM enables APCs to optimize MHC restriction and to display their antigenic peptide cargo on the surface for prolonged periods of time to be scrutinized by T cells.