Wegener's granulomatosis: a view from the granulomatous side of the disease.

Although the airway granulomata in Wegener's granulomatosis were stressed initially by Friedrich Wegener himself, in the last few decades systemic lesions mainly caused by acute vasculitis have received the most attention. However, recently, the implication of granulomatous manifestations in WG has raised much interest. The present data suggest that an aberrant Th1-type response might play a role in the initiation of WG, clinico-pathologically characterized by granulomatous inflammation rather than vasculitis. Disease progression to generalized WG with the predominance of vasculitic manifestations is associated with a "switch" or further complexity of the collective T cell response with the appearance of another subset of Th2-type cells and a less prominent Th1-type cytokine production in the granulomatous lesions of the upper respiratory tract. However, the clinical significance of the granulomatous inflammation is not yet completely understood. Further research will also have to focus on the role of the granulomata during relapsing disease. We review present knowledge of granulomatous inflammation in WG. Morphologic aspects, the scale of cytokine alterations as well as the variety of clinical manifestations are discussed.