HIGH-DENSITY-LIPOPROTEINS AND CORONARY HEART-DISEASE

An inverse relationship between the concentration of high density lipo protein (HDL) cholesterol and the development of coronary heart diseas e (CHD) is well established. It is unclear from the human studies whet her this relationship reflects an ability of HDLs to protect against c oronary disease or whether a low HDL in coronary patients is simply an epiphenomenon. Recent studies of transgenic mice, however, indicate t hat HDLs are directly antiatherogenic. The mechanism of the protection is unknown but may relate both to an involvement of HDLs in plasma ch olesterol transport and to a range of non-lipid transport functions of HDLs. It is also unclear from human studies whether specific HDL subp opulations have differing abilities to protect against CHD, although s uch specificity is suggested from studies of transgenic mice. There is circumstantial evidence that elevating the concentration of HDL chole sterol in human subjects translates into a reduced coronary risk, alth ough it should be stressed that there are still no reports of studies designed specifically to address this issue.