Immunogenetic polymorphism of lipoproteins in swine. 1. Four additional serum beta-lipoprotein allotypes (Lpp2, Lpp4, Lpp5 and Lpp15) in the Lpp system.

Four additional swine serum lipoprotein allotypes are described. Specific anti-allotype reagents were obtained from alloimmune precipitating sera produced in lipoprotein-defined-type recipients immunized with normal sera and subsequently with lipoprotein fractions. Identification studies indicate that the four serologically defined low-density lipoprotein (LDL) variants, designated Lpp2, Lpp4, Lpp5 and Lpp15, are members of a previously described Lpp system. The individual specificities, Lpp2, Lpp4 and Lpp5, are determined by three co-dominant autosomal genes, Lpp2, Lpp4 and Lpp5, respectively, whereas the common specificity, Lpp15, is controlled by a complex of genetic information of the Lpp2 and Lpp4 genes, and by the two previously described alleles, Lpp1 and Lpp3; Lpp15 occurs on the same molecule with respective individual specificity. The Lpp5 and Lpp15 antigens behave as a pair of alternative allotypic specificities. The double immunodiffusion test in agar was employed to demonstrate independent phenotypic expression of each allelic gene in the Lpp heterozygous animals, for the analysis of the immune sera, and for lipoprotein testing of 3305 sera. Marked differences in gene frequencies were found between the swine breeds tested. As a result of characteristic frequencies, only nine of 15 possible Lpp genotypes were found in the breeding herds tested; the remaining six genotypes were obtained from testcross matings.