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It was thought that intestinal epithelial cells functioned solely as a barrier to the external environment, but as described here, these cells are now known to have an integral role in facilitating and controlling crosstalk between commensal bacteria and the immune system.
IgA is the most abundant antibody class and provides a first line of defence at mucosal surfaces. Class switching to IgA occurs through both T-cell-dependent and T-cell-independent pathways, and recent studies reveal a role for commensal bacteria in intestinal IgA responses.
This Review describes how the expression of inhibitory members of the B7 family, particularly B7-H1 and B7-H4, by cancer cells, stromal cells and haematopoietic cells in the tumour microenvironment is regulated and acts to inhibit T-cell immunity, as well as the therapeutic implications.
Great progress has been made recently in the identification of genes or genetic loci that are associated with inflammatory bowel diseases. This knowledge is now providing insight into the pathogenesis of these diseases, highlighting roles for genes involved in bacterial sensing and cytokine signalling.
In this Opinion article, Stephen Galli and colleagues discuss the recent evidence that mast cells can have negative, as well as positive, immunomodulatory functions, and suggest that mast cells might have distinct roles at different phases of an immune response.
The study of T helper 17 (TH17) cells is one of the fastest-moving fields in immunology. Here, Chen Dong discusses our current understanding of this TH-cell lineage and examines some of the issues that remain to be resolved in this field.
In this Review, Reinhold Förster and colleagues highlight recent advances in the understanding of how CC-chemokine receptor 7 (CCR7) and its two ligands, CCL19 and CCL21, contribute to both immunity and tolerance.
Recent studies of T-cell leukaemia have provided insight into the molecular mechanisms responsible for the induction and progression of this disease. As discussed here, many of the genes that are dysregulated in T-cell leukaemia are known to be involved in T-cell development.
Episodes of acute inflammation must be resolved to avoid tissue damage and chronic disease. Three families of lipid mediators — lipoxins, resolvins and protectins — actively promote the resolution of inflammation through multiple mechanisms, as discussed in this Review.
In this Review, Jenny Ting and colleagues discuss the role of the NLR (nucleotide-binding domain, leucine-rich repeat containing) family proteins in various forms of cell death, including two newly recognized types of cell death — pyroptosis and pyronecrosis.
The TAM receptors — TYRO3, AXL and MER — are emerging as important regulators of innate immune responses. Here, the authors describe their roles in inhibiting inflammation driven by antigen-presenting cells, in promoting phagocytosis of apoptotic cells and in stimulating maturation of natural killer cells.
Accumulating evidence suggests that B cells can regulate immune responses. Here, the authors present a model to explain how B cells may regulate autoimmune pathology by secreting interleukin-10 in response to Toll-like receptor triggering and thereby mediate immune suppression.
Multiparameter flow cytometry can not only assess the phenotype and magnitude of a T-cell response, but based on effector function, its quality. As discussed here, the quality of a T-cell response is crucial for defining protective cellular immunity, and has great implications for vaccine design.
Natural killer (NK) cells are known to provide a first line of defence against viruses. Here, Lewis Lanier highlights the receptors and effector mechanisms used by NK cells in the protection against viruses and discusses how, reciprocally, viruses have evolved strategies to avoid activation of these cells.
The development of a diverse B-cell repertoire depends on genetic rearrangement and hypermutation at the B-cell receptor (BCR) loci. This Review describes which DNA polymerases might be involved in these DNA transactions and therefore contribute to BCR diversity.
To avoid potential damage to the host, an inflammatory response is rapidly mobilized on detection of intracellular signals that are released from dying cells. Much has been learned about these 'danger' signals, but several key issues remain unresolved, as discussed by the authors.
Maintenance of haematopoietic stem cells occurs in niches, but much discussion still surrounds the precise site and nature of these niches. Here, Mark Kiel and Sean Morrison review various niche models that are compatible with the recent published data.
A number of susceptibility genes for asthma and allergy have been identified in recent years. Here, Donata Vercelli discusses these genes and reviews the techniques used by geneticists to identify them. She also highlights the outstanding challenges in the field.
Recent advances in the structural determination of IgE and its receptors and associated molecules have provided insight into the functions and regulation of IgE. This is now helping to direct the design of new IgE-targeted therapies for asthma and allergy.
In addition to providing a physical barrier, epithelial cells have a role in initiating and maintaining allergic responses to inhaled allergens. As discussed in this Review, epithelial cells can influence the polarization of lung dendritic cells and are themselves influenced by innate and adaptive immune responses during allergic inflammation.
