Dendritic cells in venous pathologies

Dendritic cells are potent antigen-presenting cells responsible for the activation of T-lymphocytes in various immune responses. Their role in the initiation of immune reactions in allergies, autoimmune diseases, tumors, transplantation, and, more recently, in atherosclerosis has been well established, but their involvement in venous pathologies has not been previously investigated. The aim of this study was to determine whether dendritic cells are present in veins affected by varicosity and thrombophlebitis. Three groups of veins obtained at operation were studied: (1) varicose veins of the great saphenous vein from patients who were undergoing vein stripping for primary varicosity; (2) segments of the great saphenous vein from patients with varicosity complicated by thrombophlebitis; and (3) great saphenous veins without varicosity or thrombophlebitis from patients who were undergoing femoropopliteal bypass grafting. The specimens were fixed in 10% neutral buffered formalin and embedded in paraffin, and the sections were stained with antibodies to S-100 (to identify dendritic cells), CD3 (T-lymphocytes), CD68 (macrophages), von Willebrand factor (endothelial cells), alpha-smooth muscle actin (smooth muscle cells), and CD15 (mast cells) by use of avidin-biotin complex (ABC) immunoperoxidase technique. Immunohistochemical examination showed that no S-100-positive dendritic cells were present in normal saphenous veins. In contrast, S-100-positive cells with dendritic cell morphology were detected in the intima and media of veins with varicosity and thrombophlebitis, where they represented a minor cell population. S-100-positive dendritic cells were located between smooth muscle cells as well as around areas of neovascularization where they colocalized with T-lymphocytes. The present work suggests that dendritic cells might be involved in pathological processes in veins affected by varicosity and thrombophlebitis. The authors speculate that dendritic cells may be involved in the inflammatory mechanisms in these veins through their interaction with T-lymphocytes.