Real-time measurement of signaling and motility during T cell development in the thymus.

Intracellular signals arising from interactions of immature thymocytes with distinct populations of stromal cells in the thymus are central to T cell development. The characteristics of these signals and the mechanisms underlying thymocyte migration between stromal cell compartments have been difficult to identify from static measurements of fixed tissue. Recent advances in two-photon microscopy and the development of three-dimensional models for real-time studies of T cell development have shed light on how single cells navigate the thymus. These studies reveal crosstalk between thymocyte signaling and motility that may integrate the search for potentially rare self-antigens with the requirement for sustained signaling in T cell maturation.