Lipoprotein lipase (LPL) is the central enzyme in plasma triglyceride hydrolysis and is secreted by macrophages in the subendothelial space. Evidence has been provided that LPL produced by macrophages in the vessel wall exerts proatherogenic effects. Lipoprotein lipase has been difficult to purify, and its protein sequence remained undetermined until it could be deduced from the nucleotide sequence of its cDNA. The gene encodes a protein of 475aa that becomes a mature protein of 448 residues after cleavage of a signal peptide. Analysis of the sequence indicated that human lipoprotein lipase, hepatic lipase, and pancreatic lipase are members of a gene family. The atherogenic effects of LPL have been mainly attributed to its ability to favor lipid accumulation within macrophages present in the atherosclerotic lesion.