Microquantitative determination of? 1-antitrypsin by a unidimensional counterimmunodiffusion technique in capillary tubes

Abstract

To determine microquantities of α1 the immunoprecipitation test was carried out in a length of agarose gel in a capillary tube )length of gel 7–8 mm, diameter 0.6 mm). Microvolumes (about 1 μl) of antigen and antiserum were applied to the surface of the opposite ends of the gel by a microsurgical instrument. Precision of control of the manipulations with the microvolumes was ensured by means of the ocular micrometer of the MBS-2 binocular loupe. The quantity of immunoprecipitate formed in the gel was calculated from the total optical density after staining with Amido black, recorded by two-wave microspectrophotometry. The sensivity of the method is 0.3–1 ng α1-antitrypsin. The amount of α1-antitrypsin is a linear function of the quantity of precipitate formed over the range of 1–25 ng protein. The error of the method is about 10%.