Lymphocyte homing and homeostasis.
05 Apr 1996-Science (American Association for the Advancement of Science)-Vol. 272, Iss: 5258, pp 60-66
TL;DR: A review of the molecular basis of lymphocyte homing is presented, and mechanisms by which homing physiology regulates the homeostasis of immunologic resources are proposed.
Abstract: The integration and control of systemic immune responses depends on the regulated trafficking of lymphocytes. This lymphocyte "homing" process disperses the immunologic repertoire, directs lymphocyte subsets to the specialized microenvironments that control their differentiation and regulate their survival, and targets immune effector cells to sites of antigenic or microbial invasion. Recent advances reveal that the exquisite specificity of lymphocyte homing is determined by combinatorial "decision processes" involving multistep sequential engagement of adhesion and signaling receptors. These homing-related interactions are seamlessly integrated into the overall interaction of the lymphocyte with its environment and participate directly in the control of lymphocyte function, life-span, and population dynamics. In this article a review of the molecular basis of lymphocyte homing is presented, and mechanisms by which homing physiology regulated the homeostasis of immunologic resources are proposed.
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TL;DR: It is shown that expression of CCR7, a chemokine receptor that controls homing to secondary lymphoid organs, divides human memory T cells into two functionally distinct subsets, which are named central memory (TCM) and effector memory (TEM).
Abstract: Naive T lymphocytes travel to T-cell areas of secondary lymphoid organs in search of antigen presented by dendritic cells. Once activated, they proliferate vigorously, generating effector cells that can migrate to B-cell areas or to inflamed tissues. A fraction of primed T lymphocytes persists as circulating memory cells that can confer protection and give, upon secondary challenge, a qualitatively different and quantitatively enhanced response. The nature of the cells that mediate the different facets of immunological memory remains unresolved. Here we show that expression of CCR7, a chemokine receptor that controls homing to secondary lymphoid organs, divides human memory T cells into two functionally distinct subsets. CCR7- memory cells express receptors for migration to inflamed tissues and display immediate effector function. In contrast, CCR7+ memory cells express lymph-node homing receptors and lack immediate effector function, but efficiently stimulate dendritic cells and differentiate into CCR7- effector cells upon secondary stimulation. The CCR7+ and CCR7- T cells, which we have named central memory (TCM) and effector memory (TEM), differentiate in a step-wise fashion from naive T cells, persist for years after immunization and allow a division of labour in the memory response.
5,537 citations
Additional excerpts
...BIOGEN 34 38 5 Originally published as Nature 401 , 708 – 712 ; 1999 Naive T lymphocytes travel to T-cell areas of secondary lymphoid organs in search of antigen presented by dendritic cell...
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TL;DR: Much of the cellular response to IFN-gamma can be described in terms of a set of integrated molecular programs underlying well-defined physiological systems, for example the induction of efficient antigen processing for MHC-mediated antigen presentation, which play clearly defined roles in pathogen resistance.
Abstract: Interferons are cytokines that play a complex and central role in the resistance of mammalian hosts to pathogens. Type I interferon (IFN-alpha and IFN-beta) is secreted by virus-infected cells. Immune, type II, or gamma-interferon (IFN-gamma) is secreted by thymus-derived (T) cells under certain conditions of activation and by natural killer (NK) cells. Although originally defined as an agent with direct antiviral activity, the properties of IFN-gamma include regulation of several aspects of the immune response, stimulation of bactericidal activity of phagocytes, stimulation of antigen presentation through class I and class II major histocompatibility complex (MHC) molecules, orchestration of leukocyte-endothelium interactions, effects on cell proliferation and apoptosis, as well as the stimulation and repression of a variety of genes whose functional significance remains obscure. The implementation of such a variety of effects by a single cytokine is achieved by complex patterns of cell-specific gene regulation: Several IFN-gamma-regulated genes are themselves components of transcription factors. The IFN-gamma response is itself regulated by interaction with responses to other cytokines including IFN-alpha/beta, TNF-alpha, and IL-4. Over 200 genes are now known to be regulated by IFN-gamma and they are listed in a World Wide Web document that accompanies this review. However, much of the cellular response to IFN-gamma can be described in terms of a set of integrated molecular programs underlying well-defined physiological systems, for example the induction of efficient antigen processing for MHC-mediated antigen presentation, which play clearly defined roles in pathogen resistance. A promising approach to the complexity of the IFN-gamma response is to extend the analysis of the less understood IFN-gamma-regulated genes in terms of molecular programs functional in pathogen resistance.
2,956 citations
TL;DR: This review addresses the heterogeneity of TCM and TEM, their differentiation stages, and the current models for their generation and maintenance in humans and mice.
Abstract: The memory T cell pool functions as a dynamic repository of antigen-experienced T lymphocytes that accumulate over the lifetime of the individual. Recent studies indicate that memory T lymphocytes contain distinct populations of central memory (TCM) and effector memory (TEM) cells characterized by distinct homing capacity and effector function. This review addresses the heterogeneity of TCM and TEM, their differentiation stages, and the current models for their generation and maintenance in humans and mice.
2,881 citations
TL;DR: Over the past ten years, numerous chemokines have been identified as attractants of different types of blood leukocytes to sites of infection and inflammation and are now known to also function as regulatory molecules in leukocyte maturation, traffic and homing of lymphocytes, and the development of lymphoid tissues.
Abstract: Over the past ten years, numerous chemokines have been identified as attractants of different types of blood leukocytes to sites of infection and inflammation. They are produced locally in the tissues and act on leukocytes through selective receptors. Chemokines are now known to also function as regulatory molecules in leukocyte maturation, traffic and homing of lymphocytes, and the development of lymphoid tissues.
2,822 citations
Cites background from "Lymphocyte homing and homeostasis."
...Although the paths, the role of adhesion molecules in the recognition of homing sites, and several highly effective chemokines are known, it is still difficult to understand how this intricate cellular trafficking is regulate...
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TL;DR: In this paper, the chemokine receptor CCR7 was identified as an important organizer of the primary immune response in mice, and severely delayed kinetics regarding the antibody response and lack contact sensitivity and delayed type hypersensitivity reactions.
2,388 citations
References
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10,063 citations
2,778 citations
TL;DR: Although CTLA-4-deficient T cells proliferated spontaneously and strongly when stimulated through the T cell receptor, they were sensitive to cell death induced by cross-linking of the Fas receptor and by gamma irradiation, and is vital for the control of lymphocyte homeostasis.
Abstract: The role of the cell-surface molecule CTLA-4 in the regulation of T cell activation has been controversial. Here, lymph nodes and spleens of CTLA-4-deficient mice accumulated T cell blasts with up-regulated activation markers. These blast cells also infiltrated liver, heart, lung, and pancreas tissue, and amounts of serum immunoglobulin were elevated. The mice invariably became moribund by 3 to 4 weeks of age. Although CTLA-4-deficient T cells proliferated spontaneously and strongly when stimulated through the T cell receptor, they were sensitive to cell death induced by cross-linking of the Fas receptor and by gamma irradiation. Thus, CTLA-4 acts as a negative regulator of T cell activation and is vital for the control of lymphocyte homeostasis.
2,742 citations
TL;DR: Investigations have progressed from the early descriptions by intravital microscopy and histology, to functional and immunologic characterization of adhesion molecules, and now to the development of genetically deficient animals and the first phase I trial of "anti-adhesion" therapy in humans.
2,732 citations
TL;DR: In this article, the authors showed that CTLA-4-deficient mice rapidly develop lymphoproliferative disease with multiorgan lymphocytic infiltration and tissue destruction, with particularly severe myocarditis and pancreatitis, and die by 3-4 weeks of age.
2,552 citations