Visualizing T Cell Migration in vivo

Abstract

Ever since the realization that T lymphocytes are key players in the defense against pathogens and tumors, a major aim of immunologists has been to understand the relationship between the functional and migratory properties of antigen-specific T cells. The current paradigm proposes that T cells follow organ-specific trafficking pathways to exit from blood into the extravascular compartment. T cell homing is regulated at the level of adhesion molecules and chemokine receptors, whose expression is linked tightly to the differentiation state of the cell. Naïve T lymphocytes follow relatively uniform recirculation routes through secondary lymphoid organs, the molecular cues of which are fairly well understood. As effector and memory T cells must be capable of reaching virtually any site in the body, their migratory behavior is considerably more heterogeneous. During the past few years, innovative approaches for tracking T cells in vivo have emerged. Here, we review recent technical developments in experimental methods for the visualization of T cells both at the population and single cell level in vivo, and discuss what these methods have taught us about T cell trafficking.

Requirements for T Lymphocyte Migration in Explanted Lymph Nodes

“…Naive T lymphocytes recirculate and function almost exclusively in secondary lymphoid tissues, which are well supplied by blood flow. In contrast, activated T lymphocytes must function in diverse peripheral tissue sites, which may include hypoxic regions of tumors or sites of tissue injury that may be hypoxic due to damaged or abnormal vasculature (54). Thus, it is likely to be functionally important that activated T cells can migrate at lower pO 2 .…”

Visualizing dendritic cell migration within the skin

“…While genetic studies have identiWed a few molecular candidates (and will undoubtedly uncover more) without suitable tools for adequate visualization, we cannot fully appreciate how DCs co-ordinate to achieve what is, by deWnition, a highly dynamic process. Just as direct visualization signiWcantly facilitated our understanding of leukocyte rolling, adhesion and transmigration through blood vessels (Iparraguirre and Weninger 2003;Springer 1994;von Andrian and Mackay 2000), advances in microscopic techniques promise a far greater appreciation of leukocyte migration into lymphatic vessels. This will be particularly fruitful when utilized in conjunction with some of the newly developed Xuorescent markers and transgenic animals.…”

Visualization of a primary anti-tumor immune response by positron emission tomography

“…Methods used to determine the efficacy of treatment often rely on invasive techniques, such as histologic evidence of lymphocyte infiltration (2). Single time points are unable to reflect contextual influences of living organs, variations throughout the body, and the plasticity of the immune system (3).…”