Intravenous immunoglobulin (IVIg) therapy in MPO-ANCA related polyangiitis with rapidly progressive glomerulonephritis in Japan.

Jpn. J. Infect. Dis., 57, 2004 scarring is more evident in MPO-ANCA vasculitis than PR3-ANCA disease and indicates chronicity and a poorer outcome. A similar pathogenesis is responsible for other organ manifestations, for example, alveolar capillaritis in the lung is the cause of the lung hemorrhage. Serology: The association of ANCA with vasculitis has provided both a diagnostic tool and an insight into pathogenesis. Initially detected by indirect immunofluorescence of patient sera on alcohol- fixed normal human neutrophils, rapid immunoassays are now avail- able for MPO or PR3-ANCA that facilitate earlier diagnosis and identify a target for therapy. ANCA levels usually fall with therapy although it is unclear whether drug doses should be titrated against ANCA levels. The persistence of ANCA or the return of ANCA after drug withdrawal indicate a high risk of relapse. ANCA of all IgG subtypes is present and preliminary reports have observed IgM ANCA and IgG3 ANCA with more severe disease. Inhibitory anti- bodies or 'anti-idiotype' antibodies for ANCA are detectable in the circulation. Their importance is unclear but their enrichment in pooled normal human immunoglobulin has provided a rational for the use of immunoglobulin in therapy (4). Several animal models have confirmed the pathogenetic role of MPO-ANCA in vasculitis. A mouse prone to spontaneous crescentic nephritis and MPO-ANCA has been bred from an MRL/lpr back- ground. The Brown-Norway rat given mercuric chloride develops an intestinal vasculitis and MPO-ANCA. Unilateral perfusion of an MPO-immunised rat with neutrophils causes a pauci-immune glomerulonephritis, and infusion of spleen cells or MPO-ANCA from