Vasculitis and the kidney

This review analyzes the current literature on small vessel vasculitis affecting the kidney, and emphasizes the important contribution of anti-neutrophil cytoplasmic antibodies to recent advances in understanding. There is a very strong correlation between the presence of these auto-antibodies and the types of systemic vasculitis that cause crescentic glomerulonephritis with scanty immune deposits. Despite this, it is not yet clear whether anti-neutrophil cytoplasmic antibodies cause vasculitis or merely reflect its presence. However, the recent demonstration of anti-neutrophil cytoplasmic antibodies in spontaneous murine models of vasculitis, and the development of a model of vasculitis caused by immunity to myeloperoxidase strengthen the case for a pathogenic role. Regardless of whether they are pathogenic, sequential measurement of anti-neutrophil cytoplasmic antibody titres have proved extremely useful in the management of patients with systemic vasculitis. They are a considerable help in diagnosis, but perhaps they are even more important as a guide to maintenance immosuppressive therapy; relapses are rare when anti-neutrophil cytoplasmic antibodies cannot be detected, and are common when their titres are rising. Other ways to minimize exposure to cyclophosphamide are also reviewed.