ENDOTHELIAL-CELL REGULATION OF LEUKOCYTE INFILTRATION IN INFLAMMATORYTISSUES

ENDOTHELIAL cells play an important, active role in the onset and regu lation of inflammatory and immune reactions, Through the production of chemokines they attract leukocytes and activate their adhesive recept ors. This leads to the anchorage of leukocytes to the adhesive molecul es expressed on the endothelial surface, Leukocyte adhesion to endothe lial cells is frequently followed by their extravasation. The mechanis ms which regulate the passage of leukocytes through endothelial clefts remain to be clarified, Many indirect data suggest that leukocytes mi ght transfer signals to endothelial cells both through the release of active agents and adhesion to the endothelial cell surface. Adhesive m olecules (such as PECAM) on the endothelial cell surface might also 'd irect' leukocytes through the intercellular junction by haptotaxis, Th e information available on the molecular structure and functional prop erties of endothelial chemokines, adhesive molecules or junction organ ization is still fragmentary. Further work is needed to clarify how th ey interplay in regulating leukocyte infiltration into tissues.