LIPOPROTEINS CONTAINING APOLIPOPROTEIN-B ISOLATED FROM PATIENTS WITH ABETALIPOPROTEINEMIA AND HOMOZYGOUS HYPOBETALIPOPROTEINEMIA - IDENTIFICATION AND CHARACTERIZATION

Abetalipoproteinemia (ABL) and homozygous hypobetalipoproteinemia (HBL ) are inherited disorders which are classically characterized by progr essive retinal and spinocerebellar disease, fat-soluble vitamin defici ency, and absence of apolipoprotein (apo) B from the plasma, Using imm unoaffinity chromatography with an anti-apo B antiserum, we isolated a po B-containing lipoprotein (LpB) particles from the plasma of 4 ABL a nd 2 HBL patients, The LpB particles were characterized and compared w ith low density lipoprotein (LDL) and LpB isolated from normal plasma. The ABL/HBL LpB particles were similar in size and charge to normal L pB particles but were relatively enriched in several other apolipoprot eins. They contained alpha-tocopherol in a ratio to cholesterol that w as proportionately much higher than the very low ratio of alpha-tocoph erol to cholesterol in plasma. They bound saturably to fibroblasts and were internalized and degraded similarly to LDL. Hence, the molecular defects in ABL and HBL permit the secretion of a very small number of ape B-containing lipoproteins which may be important for transport of alpha-tocopherol to peripheral tissues.