The present invention provides novel methods for reducing the serine protease and/or serine protease zymogen content of a plasma-derived protein composition. Also provided are methods for manufacturing plasma-derived protein compositions having reduced serine protease and\or serine protease zymogen content. Among yet other aspects, the present invention provides aqueous and lyophilized compositions of plasma-derived proteins having reduced serine protease and/or serine protease zymogen content. Yet other aspects include methods for treating, managing, and/or preventing a disease comprising the administration of a plasma-derived protein composition having a reduced serine protease or serine protease zymogen content.