Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Nucleotide-binding oligomerization domain 2 (Nod2) is required for sensing of intracellular bacteria and subsequent inflammatory responses. Unexpectedly, new evidence suggests that Nod2 influences T helper cell signaling, proliferation and differentiation and effector responses against Toxoplasma gondii.
The differentiation of interleukin 17–producing helper T cells is controlled by a complex network of cytokines, signaling pathways and transcription factors. Regulation by microRNA particles can now be added to this list.
Antigen-driven selection in germinal centers lays the foundation of effective B cell memory. Two reports in this issue reveal novel mechanisms that control effective formation of germinal centers and their long-term persistence in vivo.
Mammalian cells ubiquitinate bacteria that erroneously enter the cytosol and target these intruding microbes for destruction by autophagy. New work shows that the protein NDP52 directly binds to ubiquitinated bacteria and facilitates the assembly of an autophagic membrane that surrounds these invaders.
Regulatory T cells that express the transcription factor Foxp3 are pivotal in suppressing autoimmune responses. A report in this issue describes a key role for interleukin 10 produced by lamina propria macrophages in maintaining Foxp3 expression during inflammatory responses in the intestine.
The induction of type I interferon is a critical checkpoint in antiviral immunity. Toll-like receptor 2 can unexpectedly induce type I interferon in the subset of inflammatory monocytes during infection with vaccinia virus.
Peptides able to positively select major histocompatibility complex class II–restricted thymocytes have not yet been defined. Two new reports identify and ascribe important extrathymic functions to several positively selecting peptides for CD4+ T cells.
Agonist encounter can divert thymocytes into several unconventional T cell subsets, many of which exhibit regulatory properties. Unexpected findings indicate that agonist selection can drive the differentiation of interleukin 17–producing cells in the thymus.
Transcription factors are critical regulators of cell fate in the hemato-lymphoid system. New evidence indicates that the basic leucine zipper transcription factor E4BP4 (also known as NFIL3) is essential for natural killer cell specification.
Cytosolic DNA sensors have remained poorly defined so far. Two recent studies identify a previously undefined cytosolic DNA-sensing pathway that depends on the RNA polymerase III–mediated conversion of microbial DNA into 5′-triphosphate double-stranded RNA that activates the RNA helicase RIG-I.
Nod2 is a cytoplasmic Nod-like receptor protein that detects the peptidoglycan subfragment muramyl dipeptide. New work shows that Nod2 also has an important role in recognizing viruses and in triggering interferon production during viral infection.
While promiscuous expression of tissue-specific antigens (TSAs) in the thymus is essential for self-tolerance, immunologically relevant TSA expression may also occur in the secondary lymphoid organs. A new study links the transcriptional regulator Deaf1 with altered TSA expression in the secondary lymphoid organs and autoimmune diabetes.
Like every metazoan species hosting a gut flora, drosophila tolerate commensal microbiota yet remain able to mount an efficient immune response to food-borne pathogens. New findings explain how the quantity of reactive oxygen species in the gut is 'tuned' to microbial burden and how intestinal immune homeostasis is thereby maintained.
Foxp3 expression is not stable and may be extinguished both in vitro and in vivo in regulatory T cells that convert into proinflammatory effector T cells. The loss of Foxp3 in regulatory T cells under autoimmune conditions may result in the conversion of suppressor T cells into highly autoaggressive lymphocytes.
Macrophages infected with human immunodeficiency virus type 1 emit long intercellular conduits that shuttle the viral protein Nef to bystander B cells, where it impairs cellular function and immunoglobulin class switching.
New work explains how the interferon-γ-regulated GTPase Irgm1 on phagosomes responds to intracellular signaling and recruits the 'machinery' for fusion with lysosomes. This pathway overlaps a signaling route controlled by bacteria to prevent the fusion of phagosomes with lysosomes.
The molecular mechanism by which thymocytes are positively selected remains incompletely understood. Three studies add a new piece to the positive selection puzzle.
Jawless fishes, the 'sister' group of jawed vertebrates, use leucine-rich repeat–containing proteins as antigen receptors. New work shows that the two isotypes of variable lymphocyte receptors are expressed in distinct lymphocyte lineages, which indicates that lymphocytes resembling T cells and B cells are an ancient feature of all vertebrates.
The thymic medulla provides a unique milieu for the induction of T cell tolerance. New work now provides a first glimpse of how thymocytes scan this microenvironment and thus maximize their chances of encountering self antigen.
Tipping the balance of early cytokine production can lead to lineage bias and, potentially, immune-mediated pathology. Mapping of a leishmania-susceptibility region has identified a gene that may determine the extent of T helper type 2 bias in naive helper T cells.
