Late effects of radiotherapy on oral mucosa in humans

In order to gain further understanding of the late effects of radiotherapy on oral mucosa, we analysed the histomorphological alterations, the cell po pulations in the subepithelial tissue, and the endothelial expression patte rn of different adhesion molecules. Biopsies were taken from patients befor e irradiation, directly after 60 Gy, and 6-12 months after radiotherapy. Be sides the histomorphological evaluation of the vessels, the endothelial exp ression of ICAM-1, VCAM-1 and E-selectin was determined as well as the dist ribution of LFA-1-, Mac-1-, VLA-4-, RM3/1-, 27E10- and 25F9-bearing cells i n the subepithelial tissue. The expression of ICAM-1 was downregulated afte r radiotherapy, whereas the percentage of LFA-1- and VLA-il-bearing cells i ncreased. VCAM-1 remained at low levels. The subepithelial infiltration was still dominated by RM3/1-positive macrophages. The number of Vessels decre ased, while the lumen of the remaining vessels increased. In conclusion, th e late effects of radiotherapy are characterized by a decreased number of b lood vessels and by significantly different expression patterns of the adhe sion molecules studied. and of integrins and macrophage subpopulations, com pared to the conditions before irradiation and directly after irradiation w ith 60 Gy.