In studies conducted by Masutani et al. on patients with idiopathic membranous nephropathy (IMN), it was shown that there is a relationship between the percentage of single IL-4-positive cells and serum IgG levels; in a group of MN patients, those with high IL-4 production had low IgG levels. This evidence concerns the gene IL4 and idiopathic membranous glomerulonephritis.