Immunological evidence for the presence of B protein (apoprotein of beta-lipoprotein) in normal and abetalipoproteinemic plasma.

The antigenicity of -lipoprotein that had been chemically altered by acetylation or arsanilation was compared with that of native beta-lipoprotein, of lymph chylomicrons, of plasma proteins with d > 1.21, and of plasma from patients with abetalipoproteinemia. Chemical alteration causes structural changes in beta-lipoprotein which render it immunologically identical with a protein that is present both in normal plasma and in plasma from patients with abetalipoproteinemia. This protein has been identified by immunoelectrophoresis as abeta -globulin which does not stain for lipid. It is presumed to be the lipid-free apoprotein of beta-lipoprotein (B protein). The findings suggest that abetalipoproteinemia is not due to inability to synthesize B protein, but might instead be due to a defect in the formation of the complete beta-lipoprotein macro-molecule.