Renal Tubular Antiproteinase (Alpha-1-Antitrypsin and Alpha-1-Antichymotrypsin) Response in Tubulo-Interstitial Damage

Abstract

We studied the role of proteinase inhibitors (Pis) α₁-antitrypsin and α₁-antichymotrypsin in relation to lysozyme (LZM), and membrane attack complex (C5b-9) in renal tubular damage by immunohistochemical techniques. Fifty-five cases, including 45 patients with glomerular diseases, and 10 controls were studied. The patients were divided into two groups; one with tubulo-interstitial lesions (TILs; 30 cases), and the other without (15 cases). Significant antiproteinase response was observed in the proximal tubules in both disease groups, indicating that they were subjected to proteolytic attack. This response correlated with proteinuria and occurred in tubules which showed protein reabsorption as demonstrated by the presence of LZM staining in consecutive serial sections. Increased deposition of membrane attack complex (C5b-9) was observed in the disease group with TILs, indicating direct damage to cell membranes. C5b-9 may also generate oxygen species, potent inhibitors of Pls, which allow the proteases to cause tubular damage.