APOLIPOPROTEIN-C-III AND APOLIPOPROTEIN-E IN APO-B-CONTAINING AND NON-APO-B-CONTAINING LIPOPROTEINS IN 2 POPULATIONS AT CONTRASTING RISK FOR MYOCARDIAL-INFARCTION - THE ECTIM STUDY

Apolipoprotein (ape) C-III and apoE are components of two major classe s of plasma lipoproteins, i.e., apoB- and non-apoB-containing lipoprot eins. To analyze the relationship between the distribution of apoC-III and apoE among lipoproteins and coronary heart disease, we compared t he distribution of these two apolipoproteins in survivors of myocardia l infarction (MI) and control subjects, within and between populations at contrasting risk for MI, ApoC-III and apoE concentrations were det ermined in plasma devoid of apoB-containing lipoproteins by immunoprec ipitation using a specific anti-apoB antiserum. These assays referred to apoC-III-Lp non-B and apoE-Lp non-B, respectively. By examining the difference with total plasma apoC-III and apoE levels, we calculated apoC-III and apoE in apoB-containing lipoproteins (apoCIII-LpB and apo E-LpB, respectively). These determinations were performed in control s ubjects and in survivors of MI, all males aged 25 to 64 years. They we re recruited in Northern Ireland and France, countries characterized b y a large difference in the incidence of coronary heart disease. In un ivariate analysis, apoCIII-LpB appeared significantly higher and the a poC-III ratio (apoC-III-Lp non-B/apoC-III-LpB) significantly lower in MI survivors than in control subjects in both countries. ApoE-LpB was higher in MI survivors than in control subjects in Northern Ireland bu t not in France. The two French and Irish control populations differed for apoC-III-Lp non-B, apoC-III ratio, and apoE ratio, which were hig her in France than in Northern Ireland, and for apoC-III-LpB, apoE, an d apoE-LpB, which were lower. Multivariate analysis showed that no par ameter involving apoC-III and apoE was more discriminatory than HDL-ch olesterol, cholesterol, and triglycerides or apoA-I, apoB, and triglyc erides between controls and MI subjects. In contrast, the apoC-III rat io was a better discriminatory parameter between the two control popul ations than the listed parameters. The differences between the two con trol populations are of particular interest because they are not biase d by the presence of disease or the large difference of the incidence in coronary heart disease between the two countries. It is suggested t hat the distribution of apoC-III among lipoproteins may play a role in the different susceptibility of the two populations to the atherogeni c process.