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

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.