ABSTRACT
Vasculitis is a condition characterized by inflammation of blood vessels. Its clinical manifestations are dependent on the localization and size of the involved vessels as well as on the nature of the inflammatory process. Vasculitis can be secondary to other conditions or constitute a primary, in most cases idiopathic, disorder. Underlying conditions in the secondary vasculitides are infectious diseases, connective tissue diseases, and hypersensitivity disorders (Table 1). Immune complexes, either deposited from the circulation or formed in situ, are in many cases involved, in the pathophysiology of the secondary vasculitides. Those complexes are supposedly composed of microbial antigens in case of underlying infectious diseases, autoantigens in connective tissue diseases, and non-microbial exogenous antigens in hypersensitivity disorders (table 1). Although immune deposits can be demonstrated in the involved vessel wall by direct immunofluorescence of biopsy material, the specificities of the antigens and their corresponding antibodies have not been demonstrated in most cases.
