The microanatomy of B cell activation.

The logistic problem of B cell antigen encounter in the lymph node has recently been studied by dynamic imaging using two-photon microscopy. These studies combined with the early studies of antigen transport have yielded a more complete picture of the orchestration of B cell activation in vivo. Here we summarize the recent advances and focus on the specialized macrophages that are critical to this process and the role of B cells themselves as antigen transporting cells.