Intravital Microscopy of T-B Cell Interactions in Germinal Centers.

Dynamic imaging analyses of antigen-specific T-B interactions in germinal centers have advanced our understanding of the molecular mechanisms underlying affinity maturation and provided a wealth of information about how follicular helper T cells function in vivo. Here we describe a routine method to visualize fluorescence protein-expressing, antigen-specific T and B cells in germinal centers. The protocol for incorporating functional reporters or genetic perturbation of the T cells by retroviral transduction is also briefly described, using the FRET-based calcium reporter as an example.