In Vivo Imaging of T Cell Immunological Synapses and Kinapses in Lymph Nodes.

T cells can become activated in lymph nodes following a diverse set of interactions with antigen-presenting cells. These cellular contacts range from short and dynamic to stable and long-lasting interactions, termed kinapses and synapses, respectively. Here, we describe a methodology to generate naïve T cells expressing a fluorescent probe of interest through the generation of bone marrow chimeras and to image T cell dynamics using intravital two-photon microscopy. In these settings, the formation of kinapses and synapses can be triggered by the administration of low and high affinity peptides, respectively. Finally, 3D cell tracking can help classify distinct T cell behaviors. These approaches should offer new possibilities for dissecting the process of T cell activation in vivo.