The visualization and characterization of two immunological forms of alpha 2 macroglobulin by immunoelectrophoretic methods.

Two peaks of alpha 2 macroglobulin (alpha 2M) were demonstrated in serum or plasma treated with trypsin using crossed immunoelectro-phoresis (CIEP). Both peaks moved the same distance in the first dimension and separated only when electrophoresed into antibody containing gel. The double peak phenomenon was shown not to be an artefact of the antiserum used and that the sample had to be fresh for both peaks to be visualised. Using the methods of staggered well CIEP and crossed thin layer gel chromatography (CTLGC) both peaks were shown to be of very similar antigenicity and molecular size. The technique of line immunoelectrophoresis (LIEP) demonstrated that the newly described lower peak was the alpha 2M/protease complex. The lowest concentration of alpha 2M/protease complexes that could be detected was 0.03 g/l. The two peaks of alpha 2M do not follow the theory of rocket immunoelectrophoresis (RIEP) and this is discussed.