Endothelial cell antigens recognized by IgA autoantibodies in patients with IgA nephropathy: partial characterization

Antibodies directed against endothelial cells (AECA) have been described in IgA nephropathy. We have previously measured AECA of the IgA subclass (AECA-IgA) in the sera of patients with glomerulonephritis by an ELISA method, and have shown that patients with IgA nephritis (IgA N) and lupus nephritis (LN) had significantly greater AECA-IgA activity compared with normal controls [1]. In the current study, on Western blotting of the EC membrane components, 6 of 18 (33%) IgA N sera positive for AECA-IgA bound to molecules of 135 and 116 kDa and 10 of 18 (56%) to a molecule of 205 kDa. These EC membrane components recognized by AECA-IgA may be of importance in the pathogenesis of IgA nephropathy.