Another approach involving the activation of the kallikrein–kinin system proposes that a specific dose of 2.5 μg/ml dextran sulfate is enough to stimulate a maximal amidase activity able to discriminate the plasma from bradykinin-mediated angioedema patients from controls and non-bradykinin mediated, while lower doses were able to stimulate only HAE-C1-INH plasmas (70). Here, KLK4 is linked to angioedema.