The addition of antigen to the buffer over the ascending and descending limbs of a free boundary electrophoresis cell containing antiserum results in an immunologically specific disturbance of the γ-globulin boundary. This technique provides a sensitive method for detecting either antigen or antibody.
The antigens studied have been bovine serum albumin, Pneumococcus polysaccharide (SSSII), Boivin-type antigen from E. coli and bovine serum globulin.
The disturbance may develop in the ascending and/or descending limb depending upon whether the antigen migrates slower, faster, or at the same rate as the antibody component.
The method detects as little as 0.1 µg of antigen/ml in the buffer and as little as 10 µg of precipitating antibody/ml in the serum compartment of the cell.
The E. coli antigen differed from the others in that it induced γ-globulin boundary disturbances when tested against normal sera, providing further evidence for the presence of antibodies against E. coli in normal sera.
The descending β-boundary disturbance frequently observed during routine free-boundary electrophoretic analysis can be eliminated by adding as little as 0.24 mg of albumin/ml to the buffer over the descending limb.
Some nonspecific boundary disturbances which may be encountered when attempting to apply this method to detect antigen and antibody are discussed.