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Signals through the pre-BCR play key roles in B cell development. New data reveal how two downstream components, SLP-65 and the tyrosine kinase Abl, regulate pre-BCR surface expression and immunoglobulin light chain expression.
The recent demonstration that T cells can recognize a single foreign pMHC complex suggests that TCR triggering does not require aggregation. Or does it?
Proteolytic cleavage generates the peptide repertoire displayed by MHC class I. Now, an interferon-γ–inducible aminopeptidase in the endoplasmic reticulum has been identified as the final player in this complex process.
Receptors in the immune system usually specialize in transmitting specific types of signals. However, by associating with two different signaling subunits, the receptor NKG2D can transmit distinct signals for either costimulation or full-fledged activation.
The source of Langerhans cells is controversial. New data show that the repopulation of these cells depends on how and to what extent, they are depleted from the skin.
CTLA-4–Ig is used to block the costimulation of T cells to interfere with their activation. This reagent may actually be working by provoking DCs to catabolize tryptophan, thereby depriving T cells and contributing to their demise.
Lipid second messengers are thought to be important in T cell activation. Two studies show the spatial-temporal organization of these lipids during immunological synapse formation and raise new questions about their functions.
A deficit of caspase-8 should presumably lead to over-activation of lymphocytes. A recent report in Nature from Lenardo's group, however, describes humans with a severe caspase-8 deficiency whose T cells, counter-intuitively, have impaired activation abilities.
Lymphocyte maturation and survival depend on a canonical NF-κB activation pathway. BAFF, however, uses an alternative NF-κB pathway to mediate signaling in maturing B cells.