Role of therapeutic plasmapheresis in ANCA-associated vasculitis.

Plasma exchange, or plasmapheresis, is a treatment method that developed over a period of two decades and involves the removal and replacement of a patient's circulating plasma. The aim of treatment is to remove disease-associated molecules and therefore interrupt disease progression. This article summarizes the developmental history of this treatment and then looks in more detail at data on the use of plasma exchange in treating antineutrophil antibody (ANCA)-associated vasculitis. The eight randomized trials and the Cochrane Systematic Review on treating renal vasculitis are summarized to show that plasma exchange may be effective in this disease, specifically in reducing the development of end-stage kidney disease (ESKD) by approximately 40%. The plasma exchange and glucocorticoid dosing in the treatment of anti-neutrophil cytoplasm antibody associated vasculitis (PEXIVAS) study is a currently enrolling study aiming to answer some of the outstanding questions relating to the use of this treatment in ANCA-associated vasculitis.

Twenty-five years of RENHIS: a history of histopathological studies within EUVAS.

In the early 1990s, an international working group of experienced renal pathologists, the Renal Histology group, set up a scoring system for biopsies with anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis. This scoring system subdivided glomerular, interstitial and vascular lesions and served as a tool for the evaluation of all renal biopsies from studies of the European Vasculitis Study Group (EUVAS). Histopathological studies gave new insights into the prediction of renal outcome in patients with ANCA-associated glomerulonephritis. Percentage of normal glomeruli and a selected number of interstitial parameters were reliable predictors of long-term follow-up glomerular filtration rate in all studies. Out of these results, a histopathological classification distinguishing focal, crescentic, mixed and sclerotic classes of ANCA-associated glomerulonephritis was developed. Until today, 13 studies have validated this classification system. Future studies will try to determine if and how renal histology could be helpful in guiding treatment of ANCA-associated glomerulonephritis.

The history of ANCA-associated vasculitis.

An essential early step toward understanding vasculitis was recognition in 1948 of the differences between the small artery disease of polyarteritis, essentially sparing the glomerulus and lungs, and disease of glomerular vessels and small veins, often involving the lungs. By 1951, Churg and Strauss drew on their knowledge of vasculitis literature and renal pathology to provide an authoritative description of the syndrome bearing their names. One year later a paper from Australia described a syndrome of febrile systemic illness with myalgias, arthralgias, microscopic hematuria, and a serum antibody reacting with neutrophil cytoplasm antigens. Within 30 years, nephrologists and immunologists in northern Europe linked antineutrophil cytoplasm antibodies to a specific vasculitis, Wegener's granulomatosis. Falk and Jennette later determined that pANCA reacted with cytoplasmic myeloperoxidase, and that cANCA did not; the antigen with which cANCA reacted was soon identified as a novel serine proteinase. New and better treatments of AAV will follow progress in understanding their pathogenesis.