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The accumulation of eosinophils in lung tissue, an invariant feature of allergic asthma, requires autocrine production of the cytokine GM-CSF. New data suggest protein isomerization mediated by the enzyme Pin1 is key to the stability of GM-CSF mRNA and eosinophil survival.
The elementary molecular structure responsible for initiating T cell receptor signaling is unknown. Distinct microclusters of a few tens of molecules may accomplish this.
Lymphocyte egress from lymph nodes is thought to require signals on T cells for the initiation of exit movement. Another possibility is that signaling instead opens endothelial 'gates' through which lymphocytes pass.
The B cell antigen receptor complex serves as a 'multipurpose machine'. Two new studies provide mechanistic insights into its activation- and anergy-related functions.
The cellular RNA helicase RIG-I initiates an antiviral response through the activation of several protein kinases. The physical link between RIG-I and these 'downstream' kinases has now been identified.
L-selectin expressed by lymphocytes interacts with specialized glycans on endothelium to mediate lymphocyte rolling. Two sulfotransferases that act cooperatively to add sulfate esters to a specific sugar residue on glycans are critical for this process.
Naturally occurring regulatory T cells are key in controlling autoimmune and inflammatory responses. New data indicate that although interleukin 2 signals are not essential for regulatory T cell development in the thymus, they are critical for maintenance of these cells in the periphery.
CD4+ T cells have been classically separated into two dominant effector populations: T helper types 1 and 2. Two new studies suggest that T cells producing interleukin 17 constitute a previously unknown lineage of CD4+ T cells.
Germinal center formation requires BCL6 to silence specific genes in B cells. New data now show that the repertoire of genes repressed by BCL6 is larger than previously thought, because of its interaction with the DNA-binding protein Miz-1.
Although it often acts as a transcriptional activator, the nuclear hormone receptor PPAR-γ also 'transrepresses' inflammatory responses mediated by the transcription factor NF-κB. New data demonstrate that sumoylation of PPAR-γ leads to the retention of repressor complexes on promoters of inflammatory genes.
Dendritic cell maturation leading to efficient antigen presentation is a central event that triggers adaptive immune responses. This maturation process seems to be regulated by the AP-1 adaptor proteins through the action of caspases.
The adaptor SAP mediates activation signals in natural killer cells. However, its family members EAT-2 and ERT are negative regulators that help to fine-tune natural killer cell recognition of viruses and tumors.
Multicellular organisms exist in hostile environments full of dangerous microorganisms. Retrocyclin 2, a θ-defensin analog, acts at cell membranes to hinder viral coat attachment helping to protect multicellular organisms.
Entry of leukocytes into tissues is a key feature of inflammation. New data suggest the polysaccharide heparan sulfate is required for several stages of this entry process.
Insects are capable of fighting viral infection even though they do not have B and T cells. Genetic analysis of drosophila C virus infection provides a glimpse of this unexplored area of innate immunity.
Fcγ receptor–mediated phagocytosis requires Rac and Cdc42 GTPases. New data show that CAPRI, a GTPase-activating protein for Ras, functions as an adaptor for Rac and Cdc42 during phagocytosis and early phases of bacterial immunity.
Lymphocytes continuously recirculate throughout the body. Evidence now suggests chemokine receptor CCR7 actively controls lymphocyte entry into afferent lymphatic vessels.
Physiological tolerance of natural killer (NK) cells to self tissues is believed to require the expression of at least one inhibitory receptor specific for self MHC. This dogma may require revision with the identification of self-tolerant NK cells lacking self MHC–specific receptors.
