Development and function of the splenic marginal zone.

The marginal zone of the spleen is a crucial region where blood-borne pathogens are sequestered by macrophages with unique arrays of scavenger molecules. In addition, a special population of B cells, which is capable of rapid activation, resides in this region. Marginal zone B cells and macrophages together form an efficient interplay between innate and adaptive immunity. The developmental pathways that lead to the formation of the marginal zone are described, and the function of the marginal zone is discussed in relation to the function of the spleen as the major blood-filtering organ of the body.