Interconversions of HDL subfractions in normolipidemic and hypoalphacholesterolemic sera incubated with fibroblasts and hepatoma cell line Hep-G2.

Gradient gel electrophoresis was used to study the changes in the HDL subfractional spectrum according to the particle size during their interaction with hepatoma Hep-G2 cells and human skin fibroblasts. Incubation of normolipidemic sera with Ch-loaded fibroblasts resulted in a drop in small particle (HDL3a' HDL3b, HDL3c) and, a rise in large particle (HDL2b, HDL2a) proportions. In contrast, incubation of the same sera with hepatoma cells caused a decrease in HDL2b proportion and a HDL3a release. Incubation of hypoalphacholesterolemic sera with fibroblasts showed a decrease in HDL3b, HDL3c particles and an increase only in HDL2a. The proportion of HDL2b rose considerably when the sera were incubated with hepatoma cells. It is concluded that not only low HDL sera levels, but also the formation of defective HDL2b particles which interact less effectively with liver cells, are characteristic of hypoalphacholesterolemia.