ABSTRACT
This chapter focuses on the role of dendritic cells (DCs) in the induction and regulation of immune responses in the intestine. DCs are divided into follicular and nonfollicular DCs. In the early 1970s, Ralph Steinman discovered a population of “tree-like” cells in cultures of splenic accessory cells, which he called “DCs” derived from dendron, the Greek word for “tree.” Immature DCs phagocytose antigen through scavenger, Fc, and C-type lectin-like receptors and capture antigens by endocytosis and micropinocytosis. In contrast to DCs, tissue macrophages lack dendrites, migrate poorly to draining lymph nodes, and inefficiently activate naive T cells. In addition to their ability to prime naive T cells, DCs determine the nature of the resulting T-cell activation. Subpopulations of DC are defined on the basis of unique surface marker expression, localization, and function. Luminal antigens, including macromolecules, bacteria, and viruses, gain access to Peyer's patches and isolated lymphoid follicles through specialized epithelial cells called microfold cells in the follicle-associated epithelium.
