Glomerular deposition of food antigens in IgA nephropathy (1)
The participation of some food antigens has been reported, and the mucosal immune system of the gastrointestinal tract has been thought to play a part in the development of this disease. This study deals with the deposition of food antigens (casein, lactalbumin, peanut protein, soybean protein, rice protein, ovalbumin) in the glomerular mesangium of patients with IgA nephropathy.
The glomerular deposition of food antigens, such as peanut protein, rice protein, ovalbumin, soybean protein, casein or lactalbumin, was observed by indirect immunofluorescence test.
The deposition of soybean protein or casein was demonstrated in the glomerular mesangium like that of IgA in the renal sections from a patient with IgA nephropathy. Casein was indicated not only in the mesangium but also along the glomerular capillary walls, but the deposition of soybean protein was principally a purely mesangial pattern. Positive results were obtained in one case (3 5%) with rice protein, 21 cases (75.0%) with soybean protein and 11 casein (39.3%) with casein, despite not finding any with peanuts protein, ovalbumin or lactalbumin in patients with IgA nephropathy. Glomerular deposition of food antigens was not observed in any controls.
The results of acid elution with citrate buffer diminished deposition of IgA, but that the soybean protein remains in the mesangium. Mesangial deposition was not demonstrated using antiser absorbed with a specific antigen, such as soybean protein or casein. Anti-food antisera (casein, soybean protein) absorbed by human IgA stained with the same pattern as did the unabsorbed antisera.
No correlations were noted between the deposition of food antigens and that of IgG, IgM or C3c. All patients had IgA1, but none had IgA2. In one case J chain was observe and in five cases SC binding was observed.
Eleven of 28 patients with IgA nephropathy were positive with soybean protein alone, nine with soy bean protein +casein, or with soy bean protein +casein + rice protein, and one was positive with casein alone. The deposition of food antigens was not found in six cases.
