Estimation of the Antitrypsin Activity of Serum

A method for the estimation of serum trypsin inhibitory capacity (TIC) was de-veloped to permit consistent results with various trypsin sources without further standardization. Very small volumes of serum are used and the results are expressed in international enzyme units. Normal women show a slightly higher mean value for TIC than normal men. Sixty-seven patients with pulmonary emphysema were surveyed: one patient homozygous for a1-antitrypsin deficiency was found. THE PRESENCE of trypsin inhibitor in the serum was described almost 70 years ago by Camus and Gley (1). Since then, there have been many papers describing diseases and conditions in which the antitrypsin activity of serum is elevated (2-7). In general, serum antitrypsin is elevated in disorders associated with acute or chronic inflammation, malignancy, and pregnancy. There are 2 principal antitryptic proteins in human serum: the 1-antitrypsin accounts for 85-90 % of the total activity, and the 2-antitrypsin, the remainder (8, 9). Interest in serum antitrypsin was stimulated recently when Laurell amid Eriksson (10