C1- inhibitor (C1(-)-Inh) catabolism in plasma of patients with hereditary angioneurotic edema (HANE) was assessed by measuring the complexes formed by C1(-)-Inh with its target proteases (C1-s, Factor XIIa, and kallikrein) and a modified (cleaved) inactive form of C1(-)-Inh (iC1(-)-Inh). This study was performed in plasma from 18 healthy subjects and 30 patients with HANE in remission: 20 with low antigen concentration (type I) and 10 (from 5 different kindreds) with dysfunctional protein (type II). Both type-I and type-II patients had increased C1(-)-C1(-)-Inh complexes (P less than 0.0001), which in type I inversely correlated with the levels of C1(-)-Inh (P less than 0.001). iC1(-)-Inh was normal in all type-I patients and in type-II patients from three families with increased C1(-)-Inh antigen, whereas iC1(-)-Inh was higher than 20 times the normal values in patients from the remaining two families with C1(-)-Inh antigen in the normal range. None of the subjects had an increase of either Factor XIIa-C1(-)-Inh or kallikrein-C1(-)-Inh complexes. This study shows that the hypercatabolism of C1(-)-Inh in HANE patients at least in part occurs via the formation of complexes with C1- and that genetically determined differences in catabolism of dysfunctional C1(-)-Inh proteins are present in type-II patients.
M Cugno, J Nuijens, E Hack, A Eerenberg, D Frangi, A Agostoni, M Cicardi
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.