Apolipoprotein AI, AII, and AIV isoforms in plasma determined by automated isoelectric focusinq with phastsystem™ and immunofixation

Abstract

Distinct genetic variants of apolipoprotein (apo) AI have been shown to influence concentrations of high-density lipoprotein (HDL) cholesterol. The genetic polymorphism of apo AIV may modulate HDL-cholesterol, plasma triglycerides, and lipoprotein(a) concentrations. There is evidence for an antagonizing role of apo AII in reverse cholesterol transport. Since genetic polymorphisms and variants of these apolipoproteins are detectable by isoelectric focusing (IEF), we developed a rapid and easy automated method for IEF analysis of apos AI, AII, and AIV on self-made or commercially available gels, using the PhastSystem™. Diluted plasma or serum samples (1 μL) are applied automatically onto the gel and IEF is carried out for 35-45 min. Afterwards, the apo A bands are precipitated by specific polyclonal antibodies and visualized by automated silver staining. This rapid procedure is suitable as a routine or screening method for IEF analysis of these major HDL apolipoproteins.