COMPARATIVE LOSS OF ACTIVITY OF RECOMBINANT SECRETORY LEUKOPROTEASE INHIBITOR AND ALPHA(1)-PROTEASE INHIBITOR CAUSED BY DIFFERENT FORMS OF OXIDATIVE STRESS

Secretory leukoprotease inhibitor (SLPI) and alpha(1)-protease inhibit or (alpha(1)-PI) are powerful antiproteases currently under investigat ion for their potential to protect the lung from neutrophil elastase ( NE). The aim of this study was to determine whether the recombinant fo rm of SLPI (rSLPI) and alpha(1)-PI show different grades of loss of in hibitory activity when exposed to reactive oxygen metabolites. We incu bated rSLPI and alpha(1)-PI with N-chlorosuccinimide (NCS), chloramine s, activated polymorphonuclear leucocytes (PMNs) and activated alveola r macrophages (AMs). Under all conditions evaluated, both antiprotease s were partially inactivated, The resulting anti-NE activity of rSLPI was not significantly different from that of alpha(1)-PI after exposur e to NCS (p>0.5), chloramines (p>0.6), activated PMNs (p> 0.07) and ac tivated AMs (p>0.9). In conclusion, recombinant secretory leukoproteas e inhibitor and alpha(1)-protease inhibitor lose antineutrophil elasta se activity to a similar extent when expressed to conditions that may be present in inflammatory lung disorders.