[Decreased plasma alpha 1-proteinase inhibitor activity in idiopathic nephrotic syndrome]

We measured plasma alpha 1-proteinase inhibitor (alpha 1-PI) levels in patients with idiopathic nephrotic syndrome (INS), chance proteinuria and/or hematuria, and normal controls to examine the roles of proteinase inhibitors in the pathogenesis of renal diseases. Plasma alpha 1-PI concentrations were significantly decreased in patients with INS at relapses and remissions of INS. The alpha 1-PI activities, anti-trypsin and anti-elastase activities, were also decreased in relapses of INS. However, the values revealed no statistically significant difference in remissions of INS. Significant correlations between the PI activities and alpha 2-macroglobulin levels were revealed, which suggested a possible contribution of alpha 2-macroglobulin to the plasma PI activities in INS. From these results we conclude that the decrease in plasma alpha 1-PI activities may be responsible for the reduction of glomerular negative charge, possibly caused by some unknown proteinase(s), and the resultant development of proteinuria.