[Measurement of secretory IgA in salivary juice and the localization of secretory IgA in duodenal mucosa in patients with IgA nephropathy].

In order to clarify whether or not the local IgA immune system plays a role on the pathogenesis of IgA nephropathy, we measured serum levels of IgA, serum and salivary levels of secretory IgA in patients with IgA nephropathy and in healthy subjects, and compared them with the results of immunohistochemical study of the duodenal mucosa obtained from patients with IgA nephropathy and healthy subjects. The results were as follows. 1. The serum levels of IgA were significantly higher in patients with IgA nephropathy than in healthy subjects. 2. The salivary levels of secretory IgA were significantly higher in patients with IgA nephropathy and non IgA nephropathy than in healthy subjects. 3. There was no significant difference in the serum levels of secretory IgA between patients with IgA nephropathy and healthy subjects, but they were significantly higher in patients with hematuria than without hematuria. 4. The salivary levels of secretory IgA were lower in some patients with IgA nephropathy, in spite of the intense staining of the secretory component and J chain in the duodenal mucosa, than in healthy subjects. On the other hand, the salivary levels of secretory IgA were lower in other patients with IgA nephropathy, in addition to the weak staining of secretory component and J chain in the duodenal mucosa than in healthy subjects. These results suggested that the disorder of IgA mucosal immunity may contribute to the pathogenesis of IgA nephropathy.