Abstract
The important role of hyperlipoproteinemia to the development of atherosclerosis have already been recognized. Most of studies on hyperlipoproteinemia have been made from the aspects of the lipid metabolism. However, studies on apolipoproteins should be very important to approach to the development of atherosclerosis. In this study immunological properties and amino acid compositions of apolipoproteins in the normal and hyperlipoproteinemic subjects (familial hyperlipoproteinemia, non-familial hyperlipoproteinemia, nephrotic syndrome, diabetes mellitus, hypothyroidism, obstructive jaundice and liver cirrhosis) were examined.
Antisera were prepared by injecting male rabbits with purified LDL, apo LDL, HDL, apo HDL and whole serum emulusified with complete Freund's adjuvant. The immunological studies were carried out by the techniques of double diffusion and immunoelectrophoresis. Protein hydrolysates (6N HCl, 110°C) of delipidated specimens of LDL and HDL were analyzed on a Hitachi KLA-5 amino acid analyzer.
Apo LDL in the normal subjects reacted with anti-whole serum, anti-LDL and anti-apo LDL, but did not react with anti-HDL and anti-apo HDL. Apo HDL in the normal subjects reacted with anti-whole serum, anti-HDL and anti-apo HDL, but did not react with anti-LDL and antiapo LDL. Apo LDL in the hyperlipoproteinemic subjects reacted with anti-apo LDL obtained from the normal subjects. These reactions were consistent with those between normal apo LDL and anti-apo LDL. The same results were observed in the apo HDL of hyperlipoproteinemic subjecta. No differences of immunological properties of apo LDL and apo HDL existed between normal and various hyperlipoproteinemic subjects. Above mentioned immunological results show that the lipoproteins increased in the various patients are same quality with those obtained from the normal subjects.
Gel-filtration of apo LDL through Sephadex G-200 produced two fractions, and fraction I was a major component. Apo HDL was seperated into six fractions, and fraction III was a major component.
Amino acid composition of apo LDL fraction I was almost consistent with that of apo LDL. Amino acid composition of apo HDL fraction III was also almost similar to that of apo HDL. Amino acid compositions of apolipoproteins obtained from the hyperlipoproteinemic subjects were almost consistent with those from the normal subjects. It is interested that there exist the patients among familial hyperlipoproteinemia whose amino acid compositions of apolipoproteins were significantly different from those of other subjects.
The precise mechanism is still unknown that, in spite of differences of amino acid compositions, no difference was observed in the immunological properties of these familial hyperlipoproteinemia.
