Anti-neutrophil cytoplasm antibodies, anti-GBM antibodies and anti-dsDNA antibodies in glomerulonephritis

Abstract. The diagnostic potential of assays detecting anti‐neutrophil cytoplasm antibodies (ANCA), anti‐GBM antibodies and anti‐dsDNA antibodies was evaluated by examining sera from time of admission in a consecutive series of 455 patients with biopsy verified primary or secondary glomerulonephritis (GN). ANCA were classified into c‐ and p‐ANCA by indirect immunofluorescence (IIF) and ELISAs using alfa‐granule extract, proteinase‐3, myeloperoxidase (MPO), elastase and lactoferrin. C‐ANCA was virtually confined to 64 patients with systemic small vessel vasculitis, 66–74% being c‐ANCA positive. P‐ANCA against MPO, seen in 47 patients, segregated through many diagnostic categories of primary and secondary severe GN. ANCA against lactoferrin and elastase were rare. Anti‐dsDNA positive patients constituted 57% of the 44 ANA‐positive patients with systemic lupus erythematosus. It is concluded that the IIF and ELISAs for anti‐proteinase‐3, anti‐MPO, anti‐dsDNA and anti‐GBM have an acceptable performance and are useful in the primary diagnostic work‐up of patients suspected for secondary GN as the majority of such patients will be classified by these assays.