Lp System of Plasma in Individuals at Risk of Developing Coronary Disease

Abstract

The Lp system of human plasma represents a genetic polymorphism of beta lipoprotein (BLp). KAHLICH KOENNER showed an increased BLp in Lpa(+) individuals compared to Lpa(–) persons. We have produced an antiserum to Lpa in order to investigate the possibility that Lpa(+) children are more likely to develop coronary artery disease as adults than Lpa(–) children. Lpa factor was isoloated from a single normal Lpa(+) donor, an Lpa(–) donor and from an Lpa(+) donor who has type II hyperbetalipoproteinemia (II BLp). The procedure for Lpa isolation included : (1) a modification of the method of Berg using 0.65 MKPO4 elution form hydroxalapatite and (2) ultracentrifugation flotation gradient at a density of 1.100 in KBR modified from Schultz. Anti-Lpa was produced by immunizing rabbits followed by absorption with Lpa(–) serum. Immunelectrophoresis revealed a pure antiserum. Anti-BLp was also prepared in order to quantitate BLp by radial immunodiffusion. Sera were typed for Lpa by agarose immunodiffusion. Investigation of 240 members of a family with II BLp revealed that segregation of Lpa was independent of the segregation of II BLp. This indicates that the BLp associated with Lpa(+) factor and the BLp associated with II BLp was controlled by different genetic loci. The presence of Lpa(+) was less of a determinant of coronary disease than II BLp. The production of anti Lpa now makes it possible to investigate other populations with various risks of coronary disease.