Purpose of review: The relationship between the concentration of high-density lipoprotein cholesterol and their protective function is addressed.
Recent findings: Strong epidemiologic evidence indicates that the concentration of high-density lipoproteins is a powerful inverse predictor of cardiovascular risk. This is consistent with the fact that high levels of high-density lipoprotein are generally associated with an increased concentration of large high-density lipoprotein particles that are now known to be the preferred acceptors of cholesterol released from macrophages via the adenosine triphosphate-binding cassette A1 pathway. Some of the protective activity, however, of high-density lipoproteins may reflect functions of specific subpopulations or variations in the 'quality' of high-density lipoprotein particles and may be unrelated to the concentration of the total high-density lipoprotein fraction. This review summarizes the cardiovascular protective role of high-density lipoproteins and addresses how the concentration and antiatherogenic activity of high-density lipoproteins are related.
Summary: Some of the protective functions of high-density lipoprotein are closely related to the simple concentration of high-density lipoproteins; others may not be related. Given the current high level of interest in therapies that raise the concentration of high-density lipoprotein, it is essential to conduct further research to identify precisely how high-density lipoproteins protect.