Elevated serum secretory IgA in patients with IgA nephropathy.

Serum secretory IgA was measured to elucidate the significance of secretory IgA in patients with IgA nephropathy. The levels of serum secretory IgA and IgA were, respectively, 6.8 +/- 3.5 micrograms/ml and 231.0 +/- 69.2 mg/dl in the controls and 11.8 +/- 3.2 micrograms/ml and 385.3 +/- 78.7 mg/dl in the patients. The levels of serum secretory IgA and IgA in the patients were significantly higher than those in controls (p less than 0.01). Elevated serum secretory IgA may reflect the excessive state of the IgA-secreting system in IgA nephropathy patients.