Erythrocyte-Bound Apolipoprotein B in Relation to Atherosclerosis, Serum Lipids and ABO Blood Group

INTRODUCTION Erythrocytes carry apolipoprotein B on their membrane, but the determining factors of erythrocyte-bound apolipoprotein B (ery-apoB) are unknown. We aimed to explore the determinants of ery-apoB to gain more insight into potential mechanisms. METHODS Subjects with and without CVD were included (N = 398). Ery-apoB was measured on fresh whole blood samples using flow cytometry. Subjects with ery-apoB levels ≤ 0.20 a.u. were considered deficient. Carotid intima media thickness (CIMT) was determined as a measure of (subclinical) atherosclerosis. RESULTS Mean ery-apoB value was 23.2% lower in subjects with increased CIMT (0.80 ± 0.09 mm, N = 140) compared to subjects with a normal CIMT (0.57 ± 0.08 mm, N = 258) (P = 0.007, adjusted P<0.001). CIMT and ery-apoB were inversely correlated (Spearman's r: -0.116, P = 0.021). A total of 55 subjects (13.6%) were considered ery-apoB deficient, which was associated with a medical history of CVD (OR: 1.86, 95% CI 1.04-3.33; adjusted OR: 1.55; 95% CI 0.85-2.82). Discontinuation of statins in 54 subjects did not influence ery-apoB values despite a 58.4% increase in serum apolipoprotein B. Subjects with blood group O had significantly higher ery-apoB values (1.56 ± 0.94 a.u.) when compared to subjects with blood group A (0.89 ± 1.15 a.u), blood group B (0.73 ± 0.1.12 a.u.) or blood group AB (0.69 ± 0.69 a.u.) (P-ANOVA = 0.002). CONCLUSION Absence or very low values of ery-apoB are associated with clinical and subclinical atherosclerosis. While serum apolipoprotein B is not associated with ery-apoB, the ABO blood group seems to be a significant determinant.