The major objective of the proposed research is to identify and quantify by radio-immunoassay the human lipopoteins, their apoproteins and the lipid processing enzymes in order to determine the role of these proteins in lipid transport in normolipidemic and hyperlipidemic subjects. The lipoproteins, apoproteins, and the enzymes, lipoprotein lipase(s) and lecithin-cholesterol acyl transferase (LCAT) will be isolated, purified and physico-chemically characterized by a combination of methods including ultracentrifugation, molecular sieve and anion exchange chromatography. Specific antibodies will be prepared and sensitive, quantitative, specific immunoassays will be developed for each of these proteins. The levels of these proteins and their companion lipids will be determined in populations of normal and hyperlipidemic adults with well-characterized cardiovascular status under steady-state conditions and in response to dietary and pharmacological perturbation in both cross-sectional and longitudinal studies of the relationship between plasma lipoproteins and the predisposition to atherosclerosis.