Hypertriglyceridemia associated with deficiency of apolipoprotein C-II.

A 59-year-old man with severe hypertriglyceridemia and no post-heparin lipolytic activity was studied because of a marked fall in plasma triglyceride concentrations after a blood transfusion. An apolipoprotein activator (apolipoprotein C-II) for lipoprotein lipase could not be detected by polyacrylamide-gel electrophoresis of apoproteins, immunodiffusion of the plasma against anti-apolipoprotein CII or activation assays for lipoprotein lipase. Furthermore, the patient's triglyceride-rich lipoproteins would not serve as substrate for lipoprotein lipase. The patient had latent post-heparin lipolytic activity, which appeared after the addition of apolipoprotein CII to the post-heparin plasma. After a transfusion of 1 unit of plasma from a normal subject the patient's plasma triglycerides fell, within one day, from 1000 to 250 mg per deciliter and remained below preinfusion concentrations for six days. We conclude that this patient's hyperlipoproteinemia resulted from a deficiency of apolipoprotein C-II.