Ultracentrifugal studies of high density serum lipoproteins in clinically healthy adults.

INDGREN and co-workers (I) have described L the properties and methodology for the ultracentrifugal study of the entire spectrum of lipoproteins present in human serum. The three most dense lipoproteins described by Lindgren et al. represent the subject of present considerations. These lipoproteins have been identified by their estimated hydrated densities as a lipoprotein of density 1.05 gm/ml, a lipoprotein of density 1.075 gm/ml, and a lipoprotein of I.145 gm/ml. At present the precise interrelationship of the chemically isolated alpha lipoproteiins described by Oncley et al. (2) to these three ultracentrifugally defined high density lipoproteins is not completely clear. Since the exact relationship to chemically isolated alpha lipoproteins remains indeterminate we have avoided the designation of the three high density lipoproteins as alpha lipoproteins and instead have utilized the following nomenclature: the lipoprotein of hydrated density 1.05 gm/ml = HDL12; the lipoprotein of hydrated density 1.075 gm/ml = HDL2; the lipoprotein of hydrated density 1.145 gm/ml = HDL3. The role of the low density lipoproteins (of hydrated density less than 1.04 gm/ml) in the systematics of serum lipid transport have been -Received for publication May -3, 1954. l This work was supported in part by the National Heart Institute, Public Health Service, The Atomic Energy Commission and the Life Insurance Medical Research Fund. 2 The designation HDL is used to indicate the high density lipoproteins for contrast with the low density group of lipoproteins for which the component of highest hydrated density is 1.04 gm/ml. The cutoff 1.04 gm/ml is arbitrary. Reference to HDLl, HDL2 or HDLS lipoprotein does not infer that a single discrete lipoprotein at each density is necessarily involved. The homogeneity or lack thereof of such lipoproteins deserves further investigation. described (3-5). Ultimate further understanding of lipid transport requires similar knowledge three of the population distributions of the high density lipoproteins and of their interrelationships with the low density group of lipoproteins. The high density lipoprotein determinations described below were made on 566 randomly chosen clinically healthy adults of both sexes, between the ages of 18 and 69 years of age.