[Kidney and vasculitis]

The kidney is affected in a variety of vasculitic syndrome. Vasculitis represent an heterogeneous group of inflammatory disease concerning vessels. They can be considered as secondary in systemic lupus erythematosus, cryoglobulinemia, rheumatoid polyarthritis but also in infectious diseases (Streptococci, hepatitis B) in malignant disease and after drugs. However, in many circumstances, no causes are found. The discovery of autoantibodies directed against components of neutrophil cytoplasm (ANCA) represent a great progress in the understanding of vasculitis. ANCA are autoantibodies directed against neutrophil lysosomial enzymes, preferentially myeloperoxidase and proteinase 3. They are frequently found in patients with idiopathic necrotizing vasculitis, systemic or localized to the kidney (Wegener granulomatosis, microscopic periarteritis, pauci-immune necrotizing glomerulonephritis, Churg and Strauss syndrome and polyarteritis nodosa). Diagnostic and prognostic values are sure, although their presence is unconstant with variable percentage in relation with the type of vasculitis. The increase of ANCA level is not always related with disease relapse. Conversely, a permanent low level means a quiescent disease. At the present time, it is not known if ANCA play a pathogenetic role or if they constitute a marker of the disease.