IgA affinity to ssDNA or endothelial cells and its deposition in glomerular capillary walls in IgA nephropathy

Autoantibodies to glomerular components may be pathogenetic in IgA nephropathy. We studied sera from 32 IgA nephropathy patients, 35 normal controls and 102 patients controls with other forms of glomerulonephritis for IgA isotype affinity to endothelial cells, denatured DNA (ssDNA), murine laminin, and cardiolipin measured by ELISA. Compared to the normal controls, patients with IgA nephropathy had significantly elevated IgA with affinity to endothelial cells (P = 0.01) and ssDNA (P = 0.04), but not to murine laminin or cardiolipin. Furthermore, serum IgA with affinity to ssDNA, but not to endothelial cells, was associated with the presence of IgA deposited in the glomerular capillary walls (P = 0.011), an indicator of poor prognosis in patients with IgA nephropathy. Therefore, IgA with affinity to ssDNA may represent an autoantibody with pathogenetic significance in IgA nephropathy.