IMPORTANCE OF LP(A) LIPOPROTEIN AND HLA GENOTYPES IN ATHEROSCLEROSIS AND DIABETES

Lp(a) lipoprotein [Lp(a)] was found in previous studies to be independ ently associated with early atherosclerosis and its sequelae. Lp(a) in vitro bound to glucosaminoglycans and was easily aggregated at physio logical Ca2+ concentration, and small Lp(a) aggregates were phagocytos ed by macrophages. Lp(a) was also found to be related to carbohydrate metabolism, and increased Lp(a) levels have been described in diabetic patients with clinical complications and were recently found in rheum athoid arthritis patients. In this study of nondiabetic male patients with documented CAD before 50 years of age and controls, a significant correlation was found between Lp(a) and IGF-1 levels. HLA class II DR 13 (DR6) was more frequent and DR15 (DR2) was less frequent II patient s than in controls. The calculated relative risk for CAD was 4.0 for D R17 (DR3), but the difference was not significant. These differences s eem to be related to high Lp(a) levels. It is suggested that phagocyto sis of preferably Lp(a) aggregates can induce an immunological tissue response that may contribute in the pathogenesis of Lp(a)-associated d iseases and may be more prominent in combination with some inherited H LA class Il haplotypes. Probably due to sex hormone effects, the assoc iation may be most pronounced in young males and in older females.