Identification of dendritic cells in ePTFE grafts explanted from humans

Following implantation different cell types interact with synthetic vascular prostheses resulting in a complex immuno-inflammatory response. Dendritic cells are responsible for activating the primary T-lymphocyte immune response in various pathological conditions by their role as antigen-presenters. This study aimed at examining whether dendritic cells accumulate within small diameter expanded polytetrafluoroethylene (ePTFE, Goretex(R)) grafts explanted from humans. Segments of expanded polytetrafluoroethylene were explanted from 11 patients (6 male, 5 female), aged between 60 and 83 years (mean 70.7 years) at secondary or revision bypass operation. The graft implant duration varied from 4 months to 12 years (mean 40.5 months). Dendritic cells were identified immunohistochemically using S-100 antibody, as well as by electron microscopy. Immunohistochemical examination showed that all 11 explanted synthetic grafts contained S-100(+) cells colonising both the synthetic matrix itself, and the adjacent perigraft tissue. Electron microscopic analysis confirmed the presence of cells with a characteristic dendritic cell morphology within the grafts. Dendritic cells which accumulated within synthetic grafts were found to co-localise with T-lymphocytes. Based on these observations, we speculate that dendritic cells may be involved in the immuno-inflammatory responses following the implantation of synthetic vascular prostheses through their interaction with T-lymphocytes.