Organogenic role of B lymphocytes in mucosal immunity

Excerpt

Gut-associated lymphoid tissue (GALT) consists of highly organized Peyer's patches (PPs) in the small intestine and intra-epithelial lymphocytes. The intestinal surface of PPs is characterized by the presence of follicle-associated epithelium (FAE)-covering "domes", regions lacking intestinal villi. M cells are found in these domes lacking microvilli on their apical surface. Therefore, the term M denotes microfold or membranous cells that are able to tunnel pathogens through the cytoplasm to the basal surface, allowing close contact with lymphocytes and macrophages. It has been shown that M cells of the respiratory epithelium can serve as the entrance gates for pathogens, such as mycobacteria (Teitelbaum et al, Immunity 1999, 10:641-50 [Abstract]). Previous in vitro studies showed that a B-cell lymphoma could effectively convert epithelial cells into M cells. This study analyzed whether B cells are responsible for the generation of FAE and M cells in vivoand whether B cell deficiency could affect transepithelial transport of an enterally-transmitted retrovirus. …