In Vivo Imaging of Tfh Cells.

Germinal centers (GCs) are microanatomical structures in secondary lymphoid organs where B cells undergo affinity maturation for antigen during the course of an immune response. This process is driven by a subset of T cells termed T follicular helper cells (Tfh) that through a multistep process gain access to the GC niche within the B cell follicle. This protocol details how to study Tfh behavior in vivo, on a single cell level, using two-photon intravital microscopy of the murine popliteal lymph node.