T lymphocytes on the move: chemokines, PI 3-kinase and beyond.

The ordered, directional migration of T lymphocytes is a key process in development, immune surveillance and the immune response. Chemokines have an important role in the guidance of T lymphocytes and activate several members of the phosphoinositide 3-kinase (PI 3-kinase) family, which contribute to various aspects of the migratory machinery in many cell systems. However, the role of PI 3-kinase in T-cell movement is unclear, and its importance has been largely dismissed. Over the past two years, there has been exciting progress in our appreciation not only of the finer details of PI 3-kinase involvement in T-cell migration, but also of other signalling events that probably influence T-cell migration in response to recognized chemoattractants. These aspects of T-cell migration are the subject of this review.