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The importance of T helper 2 cells in asthma has long been known. Now, new evidence indicates that invariant natural killer T cells might have a distinct and crucial role in the development of asthma.
In this Opinion article, a new model for the generation and the maintenance of memory B cells is proposed. The model involves these cells being continuously produced by the germinal centre throughout an immune response, with B cells that are produced later in the response being fitter and therefore having a survival advantage.
How Toll-like receptors respond to specific ligands and activate selective signalling pathways is not fully understood. This Perspective proposes a molecular mechanism, involving a series of protein conformational changes that are initiated by receptor dimerization, that might account for this specificity.
How GITR (glucocorticoid-induced tumour-necrosis-factor-receptor-related protein) regulates an immune response is not clearly understood. This article proposes a model in which the interaction of GITR with its ligand co-stimulates the respective functions of both responder T cells and CD4+CD25+regulatory T cells.
How are different memory T-cell subsets related? This is a topic of much debate; but in this article, it is suggested that the central memory and effector memory CD8+T cells that are generated after an acute infection are distinct cell lineages.
The precise point at which haematopoietic precursors commit to being T cells is a hotly debated area. Eric Jenkinson and colleagues propose that, in the fetus, commitment occurs prethymically and Notch signalling in the thymus reaffirms rather than determines such commitment.
How does a T-cell response to viral infection inform us of the state of the disease? Patterns of cytokine production by T cells could hold the key and might be useful markers for monitoring virus-associated disease in the clinic.
Chen Dong proposes that the recently identified subset of CD4+ T cells that produce interleukin-17 represent a distinct lineage of inflammatory T helper (TH) cells that develop independently of the cytokines and transcription factors that regulate TH1- and TH2-cell differentiation.
In this Opinion article, the authors propose that liver disease occurring in patients with inflammatory bowel disease is mediated by aberrant homing of gut-derived T cells to the liver, owing to abnormal expression of chemokines and adhesion molecules.
Recent data indicate that chemokines have a role in regulating dendritic-cell maturation. In this Opinion article it is proposed that this ensures that dendritic cells migrating to the lymph node arrive in a fully mature state that is optimal for T-cell priming.
In this Opinion article, Thomas Boehm proposes that quality-control mechanisms, such as the MHC peptide-presentation system, that tame immunoreceptor self-reactivity might be derived from an ancestral mechanism that guided sexual selection and similarly used information contained in intracellular peptide sequences.
