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Immunization of rabbits suffering from experimental hyperlipemia with human gamma-globulin (a total dose of 150 mg) or with disintegrated yeast Candida albicans (a total dose of 62 mg) inhibited the development of hyperlipemia and atherosclerosis. The effect was more pronounced in animals immunized on the 6th experimental week than in those immunized on the 9th week.

A procedure is described for production of artificial substrate, containing except of cholesterol and lecithin as well as the protein moiety, used in estimation of the rate of lecithin-cholesterol-acyltransferase reaction in whole blood plasma. The protein component of proteoliposomes involved total fraction of apoproteins of high density lipoproteins (HDL). The proteins containing in proteoliposomes were obtained by means of chloroform-methanol delipidation of the total HDL fraction, isolated from human blood plasma using preparative ultracentrifugation. Optimal concentration of the apoprotein in proteoliposomes was determined.

A study was made of the kinetics of the lecithin-cholesterol-acyltransferase reaction (LCAT-reaction) according to the substrate, nonesterified cholesterol of high density lipoproteins (HDLP) and of the effect produced by the medium pH and apoprotein E (apo-E) on the rate of the LCAT-reaction in blood plasma of subjects with hyper-alpha-lipoproteinemia. HDLP isolated from blood plasma of subjects with hyper-alpha-lipoproteinemia were used as substrate. Infranatants obtained from blood plasma of the test subjects after removing all lipoproteins with a density of 1.21 g/ml served as a source of the enzyme. The kinetic curve of the rate of the LCAT-reaction with one or two plateaus was found to be complex in nature; pH 7.4 and 8.0 were found to be optimal for the LCAT-reaction at high and low concentrations of HDLP, respectively. At a low HDLP concentration apo-E had no remarkable effect on the rate of the LCAT-reaction, while at a high HDLP concentration the rate of the LCAT-reaction was increased. It is assumed that more than two isoforms of LCAT are present in blood plasma of subjects with hyper-alpha-lipoproteinemia.

Variations in the blood levels of total cholesterol (C), triglycerides, low and high density lipoprotein cholesterol ( LDLPC , HDLPC ) and atherogenicity ratio were examined over time in 4841 men and 2323 women living in Leningrad. The mean values of the parameters studied were established for different age groups. Considerable differences were revealed in the blood lipid profile in men versus women. Higher levels of HDLPC and lower concentrations of LDLPC in women under 50 as compared with age-matched men account for a later development and milder course of coronary heart disease in premenopausal women.

Immunization of rabbits suffering from experimental hyperlipemia with human gamma-globulin (a total dose of 150 mg) or with disintegrated yeast Candida albicans (a total dose of 62 mg) inhibited the development of hyperlipemia and atherosclerosis. The effect was more pronounced in animals immunized on the 6th experimental week than in those immunized on the 9th week.

An ability of high density lipoproteins HDL3 to accept cholesterol from erythrocyte membranes was studied in healthy persons and in patients with ischemic disease of heart. The cholesterol-acceptory function was estimated as follows: by incorporation of fluorescent probes (cholestatriene and pyrene) into particles of HDL3, by elimination of cholesterol from erythrocyte membranes and by increase of the lipoproteins size evaluated using the method of quazi-resilient dispersion of laser light. In ischemic disease of heart the property of high density lipoproteins, specifically of HDL3 fraction, to accept cholesterol from cell membranes was impaired. Middle size of HDL3 particles was decreased in the patients with ischemic heart disease as compared with that of healthy persons.

Intravenous preinjections of rabbits with large doses of bovine serum albumin accelerated the development of experimental atherosclerosis, while subcutaneous immunization with less doses of antigen did not affect the process. Preliminary immunization of rabbits with large doses of human gamma-globulin did not accelerate the development of atherosclerosis, whereas immunization with low doses (the total dose 150 mg) even inhibited its development.

The mean cholesterol content in erythrocytes of patients, which are not impaired by hepatic diseases is 1.26 +/- 0.02 X 10-13 g/cell and it is not depended on the plasma cholesterol level.

Foam cells were isolated from atherosclerotic aortas of rabbits following their intima incubation with collagenase and elastase. The viability of the cells, their incidence and nativity were supported histochemically and electron-microscopically. The interaction of the foam cells with lipoproteins was studied in vitro with perfusions of isolated atherosclerotic aortas of rabbits during 6 hours with a medium containing beta- and pre-beta-lipoproteins labelled with I125 or simultaneously with I125 and C14-cholesterol. It was found that after the perfusion the foam cells contain a much higher proportion of radioactivity of the total lipids, cholesterol and cholesterol esters, to that of the proteins, than the perfusate. The foam cells must selectively "capture" the lipids from the lipoprotein particles. The proportion "free cholesterol/cholesterol esters" (according to the radioactivity) proved to be much higher in the foam cells than in the perfusate. The possible mechanisms of the participation of the foam cells in the metabolism of lipoproteins and in the pathogenesis of atherosclerosis are discussed.