R. Bütler

Two DNA restriction fragment length polymorphisms associated with Ag(t/z) and Ag(g/c) antigenic sites of human apolipoprotein B.

Several high frequency restriction fragment length polymorphisms (RFLPs) associated with the human gene for apolipoprotein B have been previously reported by Priestly et al.1 The EcoRI RFLP here was shown to be very strongly associated with the Ag(t/z) Immunochemlcal polymorphism of human low density llpoprotelns, allowing correct Ag(t/z) phenotyplng of 17 (out of 17 tested) unrelated individuals. The Xbal RFLP was associated with the Ag(g/c) Immunochemlcal polymorphism, permitting correct phenotyplng of 14 (out of 17 tested) unrelated Individuals. Its close association with an RFLP permitted localization of the Ag(t/z) polymorphism to the C-termlnal end of the apolipoprotein B peptlde, and allowed detailed discussion of Its probable molecular basis.

Comparative Studies on Anti‐Ag Sera in Immunodiffusion and in Passive Hemagglutination Methods

In previous publications, two of us (A.V. and G.M.) reported on isoprecipitins directed against human low density lipoprotein (LDL) which were detected in sera of multitransfused thalassemic patients from the area of Ferrara, Italy [11, 12, 131. These sera have been retested with regard to their seroIogica1 behaviour and specially to the specificity of their antibodies. The investigations included, on the one hand, comparative immunodiffusion and absorption experiments, and, on the other hand, a new and sensitive hemagglutination assay which has been previously described by two of us (R.B. and E.B.) [4]. Results of this comparative study are presented in the €allowing report.

Relationships between DNA and protein polymorphisms of apolipoprotein B

SummaryThe associations between four restriction fragment length polymorphisms (RFLPs) of the gene for human apolipoprotein B (apo B) and five antigen group (Ag) protein-polymorphisms of apo B have been investigated in 24 unrelated Finnish individuals. In this sample a complete correlation exists between the EcoRI RFLP and the Ag(t/z) polymorphism. There is strong association between the alleles of the XbaI RFLP and Ag(c/g) and a weaker one of the same XbaI site with Ag(x/y). Linkage disequilibrium is observed between the PvuII RFLP and the Ag(a1/d) polymorphism. These associations confirm that the Ag variants are true protein sequence polymorphisms of apo B.

Monoclonal antibody detects Ag polymorphism of apolipoprotein B.

A monoclonal antibody (MB‐19) was used to investigate the polymorphism of apolipoprotein B in a large family and in unrelated subjects. Apolipoprotein B was shown to exhibit high‐, intermediate‐ or low‐affinitybinding to this antibody. Thus, MB‐19 bound strongly to the Ag(c) epitope, an Ag antigenic domain previously characterized by human antisera, while it bound only weakly to the allelic epitope Ag(g). It proved therefore useful for the detection of the two corresponding allelic apoB species designated apoBc (high‐affinity binding) and apoBg (low‐affinity binding), and for confirming their co‐dominant transmission. Intermediate binding resulted from the presence of a mixture of both apoB populations in heterozygous subjects.

Ag(c): recognition by a monoclonal antibody.

A monoclonal antibody directed against human apolipoprotein B, which was previously shown in family studies to detect allelic variations (J Biol Chem 1984; 259:6423–6430), has now been identified with the Ag(c) factor. This identification allows the location of the Ag system on the structural gene for apolipoprotein B and on the short arm of human chromosome 2. The epitope corresponding to Ag(c) is located within the amino acid sequence common to apolipoproteins 8–100 and 6–48. Since a single molecule of apolipoprotein 8–100 is present on human LDL, individual LDL possesses either the epitope corresponding to Ag(c) or that corresponding to Ag(g). These studies on allelic variation among human apolipoprotein B species parallel similar studies in animals in which a relationship to atherosclerosis was found.

Genetic Polymorphism of Glycine-Rich β-Glycoprotein in the Swiss and Italian Populations

Human serum glycine-rich β-glycoprotein was genetically typed by agarosegel electrophoresis, followed by immunofixation. Analysis of a Swiss and an Italian population revealed a difference in the gene

A New Sensitive Method for Studying the Polymorphisms of the Human Low Density Lipoproteins

The group-specific, genetically determined factors of the human low density lipoproteins (LDL) were up to now determined by means of the Ouchterlony technique, using isoprecipitin containing sera from patients, or immune sera containing heteroprecipitins from animals. The disadvantages of this method have already been discussed elsewhere [3]. In particular, attention has been drawn to its relative insensitivity, and to the possibility that anti-LDL immune sera may contain non-precipitating antibodies, thus requiring other techniques for their detection. For this reason we have studied different methods of detecting non-precipitating antibodies and their possible application to our problem; the results of these investigations will be presented in detail separately. Based on the finding by BEAUMONT [l] that LDL can be fixed to erythrocytes by diazotisation, we tried to apply similar techniques to the study of the LDL polymorphisms. We limited ourselves in the beginning to the estimation of factor Ag(x) with the aid of our anti-Ag(x) serum Gi [2]. At first, the question arose whether the Ag(x) determinant was destroyed by the process of diazotisation.

Isoelectric Focusing of Human Red Cell Phosphoglucomutase (PGM1)

Gene frequencies of PGM1 phenotypes as obtained by isoelectric focusing on polyacrylamide gel in the pH range from 4 to 8 were determined in 501 samples of Swiss blood donors. Results were in good agreement with the expected distribution according to the Hardy-Weinberg law. Frequencies were PGM1a1 = 0.6278, PGM1a2 = 0.1936, PGM1a3 = 0.1297, PGM1a4 = 0.0489. Comparison with other data of the white population showed no significant differences. Isoelectric points of regular and rare gene products were determined. Application of the method in routine paternity testing is discussed.

Human Red Cell Glyoxalase I Polymorphism in the Swiss Population: Phenotype Frequencies and a Simplified Technique

A simple, cheap and rapid electrophoresis technique for the separation and detection of red cell glyoxalase is described. Frequency of GLO I1 is 0.444 and of GLO I2 0.556 respect

Detection of two apolipoprotein B species (apoBc and apoBg) by a monoclonal antibody

A monoclonal antibody (MB-19) was used to investigate the polymorphism of apolipoprotein B in a large East Finnish family and in unrelated subjects. Apolipoprotein B was shown to exhibit high, intermediate or low affinity binding to this antibody. Thus, MB-19 bound strongly to the Ag(c) epitope, an Ag antigenic domain previously characterized by human antisera, while it bound only weakly to the allelic epitope Ag(g). It proved useful for the detection of the two corresponding allelic apoB species designated apoBc (= high affinity binding) and apoBg (= low affinity binding), and for confirming their co-dominant transmission. Intermediate binding resulted from the presence of a mixture of both apoB populations in heterozygous subjects.