Rapid determination of apolipoprotein E phenotypes from whole plasma by automated isoelectric focusing using PhastSystem and immunofixation.

The influence of the genetic apolipoprotein (apo) E isoforms on human plasma lipoproteins is well established. There is, however, still a need for a phenotyping procedure applicable in laboratories not specialized in lipid research. To this end, we developed a rapid, automated electrophoresis method for apoE phenotyping. Either self-made or commercially available precasted gels can be used. Fresh or frozen samples corresponding to 0.1 microliter of plasma are applied automatically after lipid extraction in a urea-containing buffer onto the gel and isoelectric focusing is carried out for 45 min. Thereafter, apoE bands are precipitated by specific polyclonal antibodies and visualized by automated silver staining. The method is reliable, easily and quickly performed, and not restricted to specialized laboratories.