PHENOTYPIC DISTRIBUTION OF T-CELLS IN HUMAN NASAL-MUCOSA DIFFERS FROMTHAT IN THE GUT

Phenotypic and functional studies are required to understand the immun oregulatory role of mucosal T cells. Information about T cells in the human upper respiratory tract is limited and conflicting. Therefore, w e phenotyped T cells in nasal mucosa by means of multicolor in situ im munofluorescence. In normal mucosa, most CD3(+) intraepithelial lympho cytes (IELs) and lamina propria lymphocytes (LPLs) (> 90%) expressed T -cell receptor (TCR)alpha/beta, and only similar to 5% expressed TCR g amma/delta. Although most IELs in the surface epithelium were CD8(+) ( 64%), many expressed CD4(30%) and the CD4 phenotype dominated (55%) on ly slightly in the lamina propria. This result was strikingly differen t from that obtained for comparable compartments in histologically nor mal jejunal mucosa, where IELs consisted of 83% CD8(+) and LPLs of 73% CD4(+) T cells. Nasal CD3(+) IELs and LPLs were mainly CD35RO(+)CD45R A(-) and usually expressed CD7. The integrin alpha E beta 7 was, as ex pected, more common on IELs than on LPLs (78 versus 20%). In conclusio n, nasal T cells show several similarities to those of the normal jeju num but some notable differences exist, especially a relative increase in CD4(+) T cells in the epithelium and a decrease in the lamina prop ria. It should be explored whether this disparity, together with an in creased expression of epithelial adhesion molecules, might contribute to local immunological overstimulation and partly explain the relative ly high frequency of air-way allergy.