Mucosal immunity in adult primary glomerulonephritis. I. Evaluation of salivary IgA subclasses and components

Salivary components (proteins, albumin, IgA1, IgA2, IgG, IgM, beta 2-microglobulin, neopterin and peroxidase) were investigated in 3 adult types of primary glomerulonephritis (PGN): IgA mesangial glomerulonephritis (IgAGN; n = 14); idiopathic membranous glomerulonephritis (n = 8); idiopathic nephrotic syndrome (INS; n = 14), and a control group (n = 11). Salivary IgA1 levels were significantly increased in all these PGN whereas salivary IgA2 levels were only higher than controls in INS. Albumin and proteins did not differ between PGN and controls, while the IgA1 + IgA2/protein ratio was significantly increased in these 3 PGN. Salivary neopterin levels were enhanced in the 3 types of PGN, whereas beta 2-microglobulin levels were not. The other salivary components did not differ from controls. These results demonstrate the nonspecificity of the IgA increase at mucosal sites previously found in IgAGN and raise the hypothesis of an activation of mucosal immunity of PGN or of a disturbed isotypic network or lymphokine secretion in these diseases.