Volume 9 Issue 11, November 2009

T follicular helper cells are strategically positioned in germinal centres and equipped to provide the signals necessary for antibody production by B cells. This Review describes the latest studies that explore their development and function and their relationship with other T helper cell subsets.

This Review proposes an integrated model for the development of follicular versus marginal zone B cells based on the coordination of B cell receptor signal strength with signals through Notch2 and the receptor for B cell-activating factor and signals that are involved in the migration to and retention of B cells in the marginal zone of the spleen.

This Review focuses on the recent studies showing that inhibition of the nuclear factor-κB (NF-κB) pathway in epithelial cells unexpectedly results in the spontaneous development of inflammatory conditions. These results imply a role for NF-κB in these cells in controlling tissue homeostasis rather than promoting inflammation.

Time-lapse video microscopy is an important experimental tool for examining the dynamic behaviour of immune cellsin situand involves quantitative analysis of cell migration and cell–cell interactions. Here, several commonly measured parameters and imaging artefacts are described and potential solutions to detect and correct these artefacts are proposed.

Mucosal surfaces are lined by epithelial cells that establish a barrier between external environments and the internal milieu. Recent advances have uncovered mechanisms of barrier regulation by immune stimuli and, conversely, how mucosal immunity is regulated by barrier function.

The recent re-evaluation of the concept that CD4⁺T helper cell subsets are irreversibly differentiated lineages has become one of the most hotly debated issues in immunology. Here, four leaders in the field provide their thoughts on the complexities and controversies surrounding the functional plasticity of T cell subsets.