HDL (high density lipoprotein) is secreted as a small protein-rich particle by liver (and intestine).

One HDL apoproteins, A-1, activates LCAT (Lecithin-Cholesterol Acyl Transferase), which catalyzes synthesis of cholesterol esters using fatty acids cleaved from the membrane lipid lecithin.

The cholesterol is scavenged from cell surfaces & from other lipoproteins.