Abstract
The palatine tonsil is located in the strategic area of the oropharynx, and has a characteristic lymphoid architecture of secondary organs covered with reticular crypt epithelium. Narrow epithelial diverticula form the crypt and considerably increase the available surface area for direct antigenic stimulation. The mesh of the reticular crypt epithelial cells hold T and B cells, interdigitating dendritic cells and macrophages. It is speculated that reticulation of the crypt epithelium provides a favorable environment for intimate contact between cells of the immune system and crypt epithelial cells, which express a variety of molecules related to potential antigen-presentation, such as HLA-DR, ICAM-1 (CD54), VCAM-1, and co-stimulatory molecules, B7-1/137-2 (CD80/86). These phenotypes of the crypt epithelium resemble follicular dendritic cells which are professional antigen-presenting cells of lymphoid follicles. Our findings suggest that the crypt epithelial cells clearly function as antigen-presenting cells in the paratine tonsil.
