Fibronectin-immunoglobulin complexes in the early course of IgA and Henoch-Schönlein nephritis

We have previously reported the presence of circulating IgA-fibronectin complexes in adult patients with primary IgA nephropathy. In the present study five children were serially investigated during the early course of IgA nephropathy and Henoch-Schönlein glomerulonephritis. Using affinity chromatography procedures and enzyme-linked immuno-sorbent assay, IgA, IgG and IgM in complex with fibronectin were repeatedly demonstrated during the follow-up period in both groups of patients. Most patients had, at the same time, IgA, IgG, as well as IgM deposits in the glomerular mesangium. The simultaneous presence of IgA and IgG in complexes purified from serum was furthermore demonstrated. The results are thus in contrast to the findings in adults with IgA nephropathy, in whom the immunoglobulin-fibronectin complexes only contained IgA. Whether this reflects different subgroups of patients or a different pathophysiology in children and adults remains to be elucidated.