Do Human Peyer's Patches Contribute to the Intestinal Intraepithelial γ/δ T‐Cell Population?

Publisher Website
Google Scholar
Abstract
T‐cell receptor γ/δ† (TcRγ/γ†) lymphocytes in human Peyer's patches (PP) adjoining ileal mucosa were studied by monoclonal antibodies with paired immunofluorescence staining in situ and by flowcytomelric phenotyping of isolated cells. The proportion of γδ† T cells in the follicle‐associated epithelium outside the M‐cell areas (median 4·I%, range 2·2–30·1%,) was similar to that in mucosal villous epithelium (median 4·4%, range 0·5 30·5%). Most intraepithelial °/δ cells (∼90%) expressed CD45RO but only a few expressed CD8 (+ andCD3+ lymphocytes. Thesubepithelial PP dome area and interfollicular(T‐cell) zones, as well as the mucosal lamina propria. contained very few γ/δ cells (median 1·7%, range 0·4–8·9%) which were dominated (88–100%) by the Vγ 2‐encoded subset. Those in the dome area and lamina propria were often (∼75%) CD45RO+ (range 44·90%) while very few (∼2%) expressed i.‐selectin (range 0·15%). By contrast, CD45RO expression on γ/δ cells in the PPT‐cell zones was relatively low (∼46%) and that of l‐selectin relatively high (∼43%). In conclusion, TcR γ/δ+ cells are quite rare in human PP and belong mainly to the Vδ2‐encoded subset, thus being different from most inlraepithelial γδ cells that probably have another origin. The L‐selectin ‘fraction of PPγ/δ cells presumably represent newly recruited ‘naïve’ T lymphocytes while CD45RO+γ/δ cells both in PP and lamina propria arc probably antigen‐primed.