αβ T cell receptor expression in rat intestinal epithelium

Intra-epithelial lymphocytes (IEL) in normal rat small intestine have been analysed for αβ T cell receptor (TcR) expression by immunoperoxidase histochemistry on frozen sections of gut, and by immunofluorescence on isolated cells. In frozen sections, a mean value of 61% of IEL were stained by the monoclonal antibody R73, which is specific for an invariant determinant of the αβ TcR. Analysis of isolated IEL by flow cytometry gave similar results and showed that 40–62% of IEL were stained by R73. Of the IEL population as a whole, 98% of cells were LCA+, 90% CD8+ and 10% CD4+. These results for αβ TcR expression in rat intestinal IEL closely parallel our recent data for mice, and are at variance with the view that this lymphoid compartment is dominated by γδ T cells.