Abstract
Two major subfractions of high density lipoprotein (HDL), HDL2 and HDL3 were isolated by a single zonal ultracentrifugation. HDL2 and HDL3 were isolated into two distinct peaks. Isolated HDL2 and HDL3 were homogeneous in molecular size as revealed by the gradient polyacrylamide gel electrophoresis and the estimated molecular weight of each fraction were 350, 000 and 190, 000, respectively. Each fraction reacted against anti A-I and anti A-II serum but not against anti B and anti albumin serum by the double immunodiffusion technique. A-I/A-II ratio was estimated by polyacrylamide gel electrophoresis in 6M urea and revealed 3:1 in HDL3 and 10:1 in HDL2. By quantitative immunoelectrophoresis (electroimmunoassay), A-II was not detected in unconcentrated HDL2 fraction while it was observed in HDL3 fraction. A significant amount of A-I was found in both HDL2 and HDL3 fraction. Chemical analysis of HDL2 from four male subjects showed 45% of protein, 21% of cholesterol 24% of phospholipids, and 11% of triglycerides. The values for HDL3 were 60% of protein, 12% of cholesterol, 22% of phospholipids, and 6% of triglycerides. Serum specimen from a male type IIb hyperlipidemic patient subjected for analysis of HDL subfraction and found a very small peak of HDL2 against normal size of HDL3 peak. HDL subfraction of a male patient with alcoholic cirrhosis showed predominance of HDL2 with no visible HDL3 peak. Decrease in both HDL2 and HDL3 fractions was observed in a male patient with chronic hepatitis.
