Volume 6 Issue 4, April 2006

This article provides an overview of the mechanisms by which eukaryotic cells sense and respond to chromosomal double-stranded DNA breaks and describes the importance of this response for the development of lymphocytes and the development of effective innate and adaptive immune responses.

MHC class II molecules are important factors that contribute to the susceptibility of an individual to autoimmune disease. Jones and colleagues look for clues to their involvement in disease by analysing crystal structures of peptide–MHC-class II complexes.

This Review describes how tonic signalling — ligand-independent signalling from Igα–Igβ-containing receptors, such as the pre-B-cell receptor (pre-BCR) and BCR — differs from ligand-dependent signalling and then outlines recent advances in our understanding of how tonic signalling is initiated and regulated.

Regulatory T cells have a role in suppressing immune responses against tumours. Here, Weiping Zou reviews the nature of these cells, how they affect current therapeutic protocols and the ways in which their effects can be modified to improve antitumour immunity.

The caspase family has traditionally been divided into two groups: those involved in regulating apoptosis and those involved in regulating inflammation. However, as discussed in this Review, recent data indicate that capases can also regulate immune-cell development, activation and differentiation.

Evidence for crosstalk between the central nervous system and innate immune cells is accumulating. As discussed by Esther Sternberg, neural factors that first amplify and then temper pro-inflammatory responses have a crucial role in pathogen defence and in preventing toxic shock.

Chen Dong proposes that the recently identified subset of CD4⁺ T cells that produce interleukin-17 represent a distinct lineage of inflammatory T helper (T_H) cells that develop independently of the cytokines and transcription factors that regulate T_H1- and T_H2-cell differentiation.