Serological and immunohistochemical determination of von Willebrand factor antigen in serum and biopsy specimens from patients with arteritis temporalis and polymyalgia rheumatica.

Von Willebrand factor antigen (vWF-Ag) levels in serum from patients with untreated polymyalgia rheumatica (PMR) and arteritis temporalis (AT) were measured using an ELISA technique. The level in patients with AT was significantly higher (median 229%, range 182-358%) than in patients with PMR (median 190%, range 131-390%) and in controls (median 179%, range 65-296%). Using an immunoperoxidase technique and biopsy specimens from 21 temporal arteries (7 patients with AT, 7 with PMR and 7 with other diseases), vWF-Ag was localized in the luminal endothelium in all cases. VWF-Ag was also present in many new vessels along the lamina elastica of the artery wall in all patients with AT, but not in patients with PMR. We relate the higher vWF-Ag level in these patients to an increased vWF-Ag production by endothelian cells in new, proliferating vessels in the artery wall.