Transformation of cultured human monocytes by peroxidized low-density lipoprotein

To study the roles of peroxidized low-density lipoprotein (pox-LDL) during the formation of foam cells from human monocytes, monocytes isolated from normal human blood were incubated with RPMI alone, normal low-density lipoprotein (n-LDL) and copper pox-LDL, The concentrations of total cholesterol (TCH) and lipid peroxide in the human monocyte medium did not change significantly after incubation with RPMI medium alone or n-LDL, but those of TCH decreased slightly after incubation with pox-LDL for 24 h, Triglyceride (TC) concentrations in the culture medium of human monocytes decreased after incubation with all above substances, Ultrastructural studies showed that the monocytes changed to macrophages after incubation with RPMI alone or n-LDL and to foam cells after incubation with pox-LDL for 48 h. We conclude that TGs may be metabolized for ATP production by human monocytes. The energy may play a role in the transformation of monocytes to macrophages, and pox-LDL can induce transformation of monocyte-derived macrophages to foam cells.