INFLUENCE OF HDL SUBFRACTIONS ON ERYTHROCYTE AGGREGATION IN HYPERCHOLESTEROLEMIC MEN

Recent studies have suggested that theological mechanisms may be invol ved in the pathogenesis of ischemic syndromes in hyperlipidemias. We i nvestigated the association between erythrocyte aggregation and compon ents of lipoproteins in the blood of 60 normotensive, hypercholesterol emic men aged 45+/-8 years. The theological parameters assessed were a ggregation index (AI) and disaggregation shear rate threshold (gamma t ) as determined by laser reflectometry, plasma fibrinogen, total serum protein, and hematocrit. The lipoprotein variables included total cho lesterol, triglycerides, high-density lipoprotein (HDL) cholesterol an d its subfractions HDL(2) cholesterol and HDL(3) cholesterol, apolipop rotein (apo) B, apoA-I, HDL particles containing apoA-I without apoA-I I (LpA-I), and HDL particles containing both apoA-I and apoA-II (LpA-I /A-II). Covariables considered for possible confounding effects were a ge, body mass index, and smoking behavior. Fibrinogen, total serum pro tein, and both aggregation parameters (AI and gamma t) were elevated i n this hypercholesterolemic population. Univariate analysis showed tha t both AI and gamma t correlated positively with fibrinogen (P<.001) a nd total serum protein (P<.01) and negatively with HDL, cholesterol (P <.01) and LpA-I (P<.01); gamma t also provided a positive correlation with LpA-I/A-II (P<.05). A multivariate model analysis demonstrated th at HDL(2) cholesterol, LpA-I, and LpA-I/A-II also emerged as significa nt factors influencing erythrocyte aggregation; 60% to 68% of the vari ance of AI and 47% to 64% of the variance of gamma t could be explaine d by these factors. The negative relation with5 HDL(2) cholesterol, co ntaining mainly LpA-I, suggested a possible role of these HDL subfract ions in modifying erythrocyte aggregation induced by fibrinogen or oth er macromolecules. However, since LpA-I/A-II is positively related to gamma t, the possible influence of HDL particles on erythrocyte intera ctions might result from a balance between the respective effects of h eterogeneous par tides.