Plasma distribution of apoA-IV in patients with coronary artery disease and healthy controls

Recent studies showed lower apolipoprotein A-IV (apoA-IV) plasma concentrations in patients with coronary artery disease (CAD). The actual distribution of the anti-atherogenic apoA-IV in human plasma, however, is discussed controversially and it was never investigated in CAD patients. We therefore developed a gentle technique to separate the various apoA-IV containing plasma fractions. Using a combination of precipitation of all lipoproteins with 40% phosphotungstic acid and 4 MgCl2, as well as immunoprecipitation of all apoA-I-containing particles with an anti-apoA-I antibody, we obtained three fractions of apoA IV: lipid-free apoA-IV (about 4% of toga apoA-IV), apoA-IV associated with apoA-I (LpA-I:A-IV, 125), and apoA-I-unbound but lipoprotein-containing apoA-IV (LpA-IV, 84%). We compared these three apoA-IV fractions between 52 patients with a history of CAD and 52 age- and sex-matched healthy controls. Patients had significantly lower apoA-IV levels when compared to controls (10.28 +/- 3.67 mg/dl vs. 11.85 +/- 2.82 mg/dl, P = 0.029), but no major differences for the three plasma apoA-IV fractions. We conclude that our gentle separation method reveals a different distribution of apoA-IV than in many earlier studies. No major differences exist in the apoA-IV plasma distribution pattern between CAD patients and controls. jlr Therefore, the antiatherogenic effect of apoA IV has to be explained by other functional properties of apoA IV (e.g., the antioxidative characteristics).