Immunochemical Quantitation of Human C1 Esterase (C1s): Concentration in Normal Serum and Purification Yields

Abstract

Abstract Immunochemical quantitation of C1s is possible with the single radial immunodiffusion technique. C1s is the complement component with the lowest concentration for which this technique has been used. The normal adult concentration is 32.8 ± 6.2 µg/ml (1 S.D.). The C1s concentration in normal human serum is relatively insensitive to the method of storing and collecting blood samples. Sera or EDTA plasma can be kept at 0°C, -20°C or -70°C, so this should be a practical method for clinical laboratories. Clinical studies in various disease states are in progress. Using this method, the recovery and overall yield at each stage of purification as well as the specific hemolytic and esterase activities were calculated. The overall yield of C1s averaged 3% to 4% with specific hemolytic activities of 150,000 to 350,000 site-forming units/mg, and specific esterase activities ranging from 1500 to 2500 units/mg. These figures are the best obtained to date, but with increasing knowledge of this important serum enzyme more rigid criteria of purification are being determined with the goal of achieving high constant specific activity. The yields at various steps should be helpful in redesigning the methods of purification.