Identification of alpha1-lipoproteins in crossed immunoelectrophoresis.
Evans Blue dye binds selectively, but with different avidities, to five major antigens in human serum. The anodic mobility of the antigen-dye complexes is greater than that of the antigens alone in crossed immunoelectrophoresis, which is of practical value for identification. We used this characteristic to show that in some human sera there is a population of alpha1-lipoprotein molecules that migrates electrophoretically in the beta-lipoprotein region, where in conventional zone electrophoresis it could be mistaken for beta-lipoprotein. We also demonstrate that horses, unlike rabbits, rarely make precipitins to human serum alpha1-lipoprotein. Equine antiserum to human serum therefore generally is useless for detecting this important serum antigen in immunoelectrophoresis.