Lymphatic endothelium of the human tongue expresses multiple leukocyte adhesion molecules

The expression of leukocyte adhesion molecules on lymphatic vessels of the human tongue was examined using histochemical and immunohistochemical methods. Three different types of lymphatic vessels were distinguished: type I vessels expressed intercellular adhesion molecule-1 (ICAM-1), platelet-endothelial cell adhesion molecule-1 (PECAM-1), and endothelial cell-selectin (ELAM-1); type II vessels expressed ICAM-1 and PECAM-1; and type III vessels expressed PECAM-1 only. The lymphatic vessels located very close to the oral epithelium (lymphatic capillaries) and the other lymphatic vessels near the oral epithelium were type I. The lymphatic vessels in the submucosal connective tissue (collecting lymphatic vessels) were type II and type III. The results suggest that there may be functional differences in the lymphatic endothelium, where lymphatic capillaries are more active than collecting lymphatic vessels in lymphocyte migration from tissue into the lymphatic vessels.