Objective. To elucidate the role of antiendothelial cell antibodies (AECA) in vascular inflammation in patients with Wegener's granulomatosis (WG). Methods. IgG fractions from 3 AECA-positive WG patients, IgG from 3 AECA- negative WG patients, and IgG from healthy donors were tested for their ability to: a) bind to endothelial cells and to display complement-dependent or antibody-dependent cellular cytotoxicity, b) modulate cell membrane expression of adhesion molecules, as evaluated by cytofluorometry and by immunoenzymatic assay, and c) induce the secretion of interleukin-1β (IL- 1β), IL-6, IL-8, and monocyte chemotactic protein 1 (MCP-1). Results. We found that AECA IgG from WG patients do not display any significant cytotoxicity but are able to up-regulate the expression of E-selectin, intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 and to induce the secretion of IL-1β, IL-6, IL-8, and MCP-1. Conclusion. AECA in patients with WG could play a potential pathogenetic role by activating endothelial cells, and thus facilitating leukocyte recruitment and adhesion to endothelial surfaces, rather than by displaying a cytotoxic activity.
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