Distribution, activity and concentration of cathepsin B and cystatin C in the wall of aortic aneurysm.

Intensity of immunohistochemical reaction to cathepsin B is stronger and to cystatin C weaker in the wall of aortic aneurysm than in normal aorta. Localization of cathepsin B and cystatin C in the aneurysm wall is different from that in the control aorta, but activity and concentration of cystatin C in the aneurysmal wall is lower than in normal aorta. The parietal thrombus of aneurysm also shows high activity of cathepsin B. The obtained results point to participation of cathepsin B in degradation of aneurysmal structural proteins and in enlargement of the aneurysmal size.