C1 inhibitor: evidence for decreased hepatic synthesis in hereditary angioneurotic edema.

Although the Cl inhibitor was detected in 5 to 10 percent of normal hepatic parenchymal cells by means of the immunofluorescent technique, none was seen in liver biopsies from two individuals with hereditary angioneurotic edema having low concentrations of Cl inhibitor in the serum. In contrast, the percentages of cells which reacted with fluorescent antiserums to C4 and transferrin were normal. These data suggest that in most subjects with hereditary angioneurotic edema, there is decreased synthesis of the C1 inhibitor but normal synthesis of C4, and that the disease results from this biosynthetic error.