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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.
