Factors governing the intranodal migration behavior of T lymphocytes

With the advent of two-photon microscopic imaging, the last few years have witnessed remarkable progress regarding our understanding of the movement behavior and interaction dynamics of different immune cells within lymphoid organs. The basal intranodal motility of naive T lymphocytes in the absence of antigenic or inflammatory stimuli, although at first glance representing a phenomenon of apparent simplicity, is far from being completely understood. The most important open question in this context relates to the origin of intranodal T-cell motility itself: how are these highly dynamic cells 'motivated' to carry out their relentless scanning of dendritic cells present in the lymph node (LN)? This review summarizes recent advances in the search for factors governing the intranodal migration behavior of naive T lymphocytes, focusing in particular on the role of extracellular pro-migratory cues, intracellular signaling components, and the influence of the structural LN environment on intranodal T-cell motility.