In the marginal zone of the spleen the bloodstream passes through an open system of
reticular cells and fibers in which various myeloid and lymphoid cells are located.
Macrophages in this region are well equipped to recognize pathogens and filter the blood by
virtue of unique combinations of pattern recognition receptors. They interact with a specific
set of B cells that can be found only in the marginal zone and that are able to react rapidly to
bacterial antigens in particular. This combination of strategically located cells is an important …