Neutrophil and endothelial cell activation in the vasa vasorum in vasculo-Behcet disease

Aim: The aim of this study was to analyse the immunopathological mechanisms of vasculo-Behcet disease, which were also compared to cases of Takayasu's arteritis and inflammatory aneurysm to evaluate differences in inflammator y mechanisms. Method and results: We reviewed six cases of vasculo-Behcet disease, four o f Takayasu's arteritis and seven inflammatory aneurysms which underwent sur gical repair. Immunohistochemical studies were performed on paraffin-embedd ed tissue using a labelled streptavidin-biotin method, as was in-situ hybri dization for Epstein-Barr virus. Microscopically, neutrophils and lymphocyt es accumulated around the vasa vasorum. Neutrophils were prominent as compa red to Takayasu's arteritis and inflammatory aneurysm. Elastic fibres were not severely destroyed. Endothelial cells (ECs) of most vasa vasorum expres sed HLA-DR. The number of vasa vasorum around which inflammatory infiltrati ng cells were observed in vasculo-Behcet disease was significantly greater than in inflammatory aneurysms and Takayasu's arteritis (P < 0.001). The cy tokines IL-1 alpha, TNF-beta and IFN-gamma were expressed in neutrophils an d lymphocytes which were distributed around vasa vasorum, as well as neutro phils adherent to HLA-DR positive ECs. Conclusion: Our results suggest that vasculo-Behcet disease should be class ified as a neutrophilic vasculitis targeting the vasa vasorum. Aneurysm for mation may be related to degeneration of arterial wall caused by inflammati on of the vasa vasorum.