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Proteins are digested into peptides for presentation by MHC to T cells. A recent paper in Science reports that some lipids also undergo processing in order to be presented by the unconventional class I protein CD1.
New data shows that NADPH oxidase activation by Rac2 involves an insert-dependent interaction between Rac2 and cyt b. This unique activation mechanism has far-reaching implications for the regulation of related signaling systems.
In addition to the TCR and classical MHC class I, MHC class 1–like molecules can interact with a variety of receptors that play a role in T cell activation. Engagement of NKG2D on CMV-specific αβ CD8+ cells by MIC was found to provide them with a costimulatory signal and augment their cytotoxic response.
Notch is heavily involved in T cell lineage commitment . . . or is it? New data indicates that neither CD4 nor CD8 cell maturation is Notch1-dependent, whereas Notch1 is critical for earlier steps in T cell development.
What determines whether immune responses against a self-peptide can evoke an anaphylactic response? New evidence describes anaphylaxis that appears to be governed by thymic expression of the self-antigen.
A minimal half-life of the TCR-pMHC interaction is required for complete T cell signaling (the kinetic proof reading model). In an extension to this model it is clear that the dwell time or half-life of TCR-pMHC interaction is also critical for T cell activation
Secretion of IFN-γ by T cells is usually the result of antigen stimulation. However, a newly identified GADD45β pathway can implement IFN-γ production after exposure to cytokines IL-18 and IL-12 without need of antigen.
Three recent papers in Nature describe ICOS-deficient mice. ICOS is necessary for normal antibody responses and may be protective against autoimmunity.
The proliferation and differentiation of hematopoietic stem cells is regulated by BMP-4 and Shh. These factors collaborate with cytokines in the bone marrow to create an environment that maintains stem cell homeostasis
Human hematopoietic stem cells are of vital scientific and clinical importance. Using high resolution clonal analysis, Dick and colleagues shed important new light on the developmental behavior of these cells in the context of an in vivo model system.
The immunomodulatory character of bacterial CpG DNA is well known. A report in a recent issue of Nature pinpoints a Toll-like receptor as the cellular accomplice in this innate immune reaction.