Heterogeneity of human serum beta-lipoprotein.

Human serum beta-lipoprotein (specific gravity 1.063 to 1.007) has previously been shown to form two lines on immunoelectrophoresis. In the study of a large number of individual sera it appears that both are not always present, that they are present in varying amounts in normal individuals, that a third form sometimes exists, that they are not separable by sedimentation techniques, and that they crossreact immunologically. These can also be demonstrated on starch gels and starch gel immunoelectrophoresis, one form entering the gel and the other remaining at the origin.