New perspectives in pulmonary angiitis - From pulmonary angiitis and granulomatosis to ANCA associated vasculitis

Traditionally clinical and histopathological features were mainly relied on for classification of vasculitis and granulomatosis of the lung. These can be complemented by immunodiagnostic features which contribute to the class ification as well as to the understanding of the pathogenesis of these diso rders. Previously five conditions were classified together under the headin g "pulmonary angiitis and granulomatosis" (PA & G), mainly on the basis of histological similarities. These conditions have in common a granulomatous histopathology together with necrosis of varying degree, pulmonary vasculit is and occasionally systemic vasculitis. The introduction of novel immunodi agnostic methods led to different approaches of classification, specificall y a separation between a group of disorders associated with antinuclear ant ibodies (ANA), referred to as collagen vascular diseases, and a group of sy stemic autoimmune diseases unrelated to ANA, referred to as primary systemi c vasculitides. Among the latter Wegener's granulomatosis (WG), Churg-Strau ss syndrome (CSS) and microscopic polyangiitis (MPA) are associated with a group of autoantibodies (antineutrophil cytoplasmic antibodies-ANCA) which separate them from other members of the PA & G group. The granulomatous and vasculitic disorders WG and CSS together with the non-granulomatous small- vessel vasculitis MPA now form a new group of diseases ('ANCA-associated va sculitides') which have many clinical, serological and immunohistochemical features in common. Collagen vascular diseases (CVD) are serologically char acterized by distinct subspecificities of antinuclear antibodies (ANA), som etimes pronounced hypergammaglobulinaemia, complement consumption and immun e deposits (antigen-antibody-complement complexes) which are common in situ in immune-complex vasculitis. In this article newer aspects of the clinica l course, the immunodiagnostic procedure, and the immunopathogenesis of the relatively large group of pulmonary angiitis will be described.