Study on an improved isolation method of human α1-antichymotrypsin and the measurement using radioimmunoassay in various human body fluids

α1-antichymotrypsin (α1AC) is known to specifically inhibit the activity of chymotrypsin-like proteases, and considered to be one of the acute phase reactants. In our previous study, the α1AC level was increased in gastric juice from the patients with gastric cancer, when compared to those in benign gastrointestinal disorders or normal controls, α1AC was purified from serum using the method of salting out and gel chromatography which was modified from the method of Travis, et al. The moleculer weight of the purified α1AC was 58, 000 daltons by SDS-polyacrylamide gel electrophoresis, which was completely identical to the report by Lame and Hayem. The new highly specific and sensitive radioimmunoassay (RIA) was established for α1AC. The RIA was prepared using the purified α1AC and anti-α1AC antibody commarcially available. The α1AC level was first determined in some human body fluids, such as gastric juice, bile, ascitic, pleural, cerebrospinal and synovial fluids.