[Mesangial proliferative glomerulonephritis].

IgA nephropathy is by far the most popular mesangial proliferative glomerulonephritis which can induce nephrotic syndrome. The etiology and pathogenesis of IgA nephropathy are still elusive, however. The enigma is that the IgA molecules deposited in glomeruli are mainly IgA1 subclass produced in central lymphoid organs and not the IgA2 subclass produced in peripheral mucous membrane, contrary to the notion that mucosal defense mechanism may be exacerbated in patients with IgA nephropathy. Recent investigations have elucidated that clearance of IgA might be deteriorated in these patients due to the abnormalities in the O-glycosylation of the hinge region of IgA molecules. The etiopathogenesis of IgA nephropathy elucidated in recent years is discussed.