Haemophilus parainfluenzae antigen and antibody in children with IgA nephropathy and Henoch-Schonlein nephritis

Although the pathogenesis of immunoglobulin A (IgA) nephropathy and Henoch- Schonlein nephritis (HSN) remains uncertain, there is substantial evidence that they are immune complex-mediated diseases. Recently, Haemophilus parai nfluenzae antigens were shown in the glomerular mesangium of adult patients with IgA nephropathy, and greater levels of IgA antibody against H parainf luenzae were also shown in the sera of adult patients with IgA nephropathy. The present study was performed to detect H parainfluenzae antigens and an tibody against ii parainfluenzae in children with IgA nephropathy and HSN. H parainfluenzae antigens in the mesangium were examined by indirect immuno fluorescence, and antibody against H parainfluenzae was examined by enzyme- linked immunosorbent assay Diffuse global staining of the mesangium with ra bbit antisera against H parainfluenzae was shown in 10 of the 32 patients ( 31%) with IgA nephropathy and 12 of the 34 patients (35%) with HSN, Convers ely, only 2 of the 47 patients (4%) with other renal diseases showed staini ng of glomeruli with rabbit antisera against H parainfluenzae (IgA nephropa thy versus other renal diseases, P = 0.003; HSN versus other renal diseases , P = 0.0006). Patients with IgA nephropathy and those with HSN showed sign ificantly greater levels of plasma IgA1 antibody against H parainfluenzae t han patients with other renal diseases (IgA nephropathy versus other renal diseases, P = 0.008; HSN versus other renal diseases, P = 0.025). These fin dings suggest that H parainfluenzae has a role in the cause of these two co nditions in a subset of patients. (C) 2000 by the National Kidney Foundatio n, Inc.