The genetic polymorphism of the fourth component of human complement: methodological aspects and a presentation of linkage and association data relevant to its localization in the HLA region.

The C4 polymorphism in man has been studied by immunofixation electrophoresis, crossed immunoelectrophoresis, and functional detection after agarose gel electrophoresis. It has so far not been possible to reveal this polymorphism by isoelectric focusing and functional detection of C4 bands. Three common alleles and one less frequently occuring allele have been identified. In a small population sample studied by all the different techniques and verified by family segregation, the following gene frequencies have been found: C4F: 0.46, C4S: 0.32, C4F1: 0.20, and C4M: 0.02. By linkage and association studies in a family material it has been shown that a structural C4 locus is situated in the HLA region of chromosome 6 very close to the HLA-B and Bf loci.

Metabolic studies of C3 in man.

The results of metabolic studies with radioactively labelled C3 in 14 healthy individuals are presented. Plasma volume determined by labelled C3 was generally higher than when determined by labelled albumin, and different batches of C3 behaved differently during the early part of the experiments. These phenomena are probably caused by C3 inhomogenities which are difficult to detect by usual biochemical and immunological methods. We have, therefore, excluded the first 24 h of the experiments from the mathematical analysis. In this way, rather narrow limits for the metabolic parameters have been obtained.

Serial complement studies in a patient with Goodpasture's syndrome treated with bilateral nephrectomy and renal transplantation.

A young male patient with Goodpasture's syndrome was treated with bilateral nephrectomy and when antiglomerular basement membrane antibodies could no longer be detected he received a cadaveric renal homograft. Fifteen months later he is in good health and without signs of pulmonary disease. Renal function is satisfactory, and there are no findings indicating recurrence of the nephritis. Serial complement studies during the entire course revealed varying degrees of activity in the sequence in the different phases: a high degree of in vivo activation of complement was found in the period before the nephrectomy, there was a moderate degree of activation in the period between the nephrectomy and transplantation and, finally, there were no signs of activity in the system after transplantation. This investigation strongly suggests that the complement system is of definite pathogenetic significance in this human equivalent to experimental nephrotoxic nephritis.

Complement loci of the HLA complex. Studies on families with intra-HLA crossovers and haplotype associations.

We report genetic studies of families with defined crossovers in the HLA complex. Haplotypic associations between the different alleles have been analyzed. The object of the studies has been to determine the precise location of complement loci on the HLA complex on chromosome 6. Based on direct observation of recombinations and on indirect evidence from haplotypes, we postulate that the C4 and Bf loci are located between the HLA-B and -D regions and probably closer to the former. Available information also points towards the same localization for the C2 locus.

In vivo activation of C3 revealed by crossed immunoelectrophoresis as a parameter of immunological activity in disease.

A technique suitable for the demonstration of in vivo activation of the third component of complement (C3) is described, and the results of detailed methodological studies are presented. The technique is a useful tool for monitoring the activity of the humoral immune system in disease states. The serum levels of complement components reflect a balance between synthesis and catabolic rates, while the present method gives a more dynamic picture of the state of the complement system. The results of the application of the technique to different groups of patients are presented.

Effect of exercise training in patients with essential hypertension.

The aim of the present study was to examine the effect of regular exercise training in moderate essential hypertension. Twenty subjects (one woman and 19 men) trained for 45 minutes three times a week for 12 weeks, to 60% of their maximal heart rate. Blood pressure was measured at rest and during a maximal exercise test on bicycle ergometer. All subjects achieved training effect measured as a significant reduction in heart rate at comparable submaximal work level and a significant increase in duration of exercise. Diastolic blood pressure at rest decreased from 107 +/- 7 to 101 +/- 5 mmHg (P < 0.01), and at corresponding submaximal exercise level 116 +/- 11 to 106 +/- 11 mmHg (P < 0.01). No significant reduction in systolic blood pressure was found. Exercise training might in some patients with moderate essential hypertension be an alternative to pharmacological treatment.

Complement system studies in systemic lupus erythematosus (SLE)

Complement system involvement has been studied in 16 patients with systemic lupus erythematosus (SLE). Circulating conversion products of C3 were observed in 4 cases. Low mean values of C4 and C3 were found, while C3 proactivator (properdin factor B) levels were low in only a few of the patients. The levels of C4, C3 and C3 proactivator were not lower in the 4 patients in whom C3 conversion products could be demonstrated than in the others. It is concluded that the low complement values found in SLE may be caused mainly by deficient synthesis. Signs of complement activation are in this patient material demonstrated early in the disease, and chiefly in patients not receiving immunosuppressive therapy.

Humoral immune system activity in inflammatory bowel disease.

In vivo activation of complement components C3 and GBG as revealed by crossed immunoelectrophoresis reflects humoral immune system activity in disease. These methods have been applied to a material of 25 patients with ulcerative colitis (UC) and 29 patients with Crohn's disease (CD). Signs of activity in the complement sequence were observed in approximately half the patients of both categories. Fifty blood samples from 30 healthy controls were all negative. The presence of complement activation was correlated with disease activity in both groups, and in patients with CD this could also be shown in longitudinal studies in single patients. In UC complement activation was correlated with the extent of the disease process. The serum levels of factors C4, GBG, and C3 in the patient groups did not differ significantly from those found in the normals.

Properdin factor B (Bf) polymorphism in Norway.

Bf phenotype distribution and Bf allele frequencies in samples of the Norwegian population and the Lappish minority of Norway are presented. Bfs in Norwegians was found to be 0.817, while it was 0.888 in Lapps. The difference is statistically significant. Possible explanations of this difference are discussed. It is noted that Bf allele frequencies of Norwegians are similar to those of Germans, while differing from frequencies found in US whites.

Genetics of LCAT (lecithin: cholesterol acyltransferase) deficiency.

Since 1967 a syndrome characterized by renal disease, normochromic anaemia and corneal opacities has been described in 7 members of 3 different Norweigan families. The patients have low levels of esterified cholesterol and lack LCAT (lecithin: cholesterol acyltransferase) activity in plasma. The genetic basis of the disorder seems to be the presence of a LCAT deficiency gene in double dose. This gene is probably the result of a single mutational event. Linkage studies revealed non-random assortment between LCTA deficiency and serum haptoglobin (Hp) types. After Hp subtyping a combined lod score of 3-41 at a recombination fraction of 0-00 was obtained. Association was revealed between the LCAT deficiency gene and the Hp-1S gene. We propose that the LCAT gene is situated close to the alpha-haptoglobin locus on chromosome no. 16.

Electrophoretic polymorphism of human C4 is due to charge differences in the alpha chain, presumably in the C4d fragment.

Various common C4 gene products were isolated from serum by immunoprecipitation. After reduction the C4 alpha-, beta-, and gamma-polypeptide chains were studied by two-dimensional electrophoresis. Isoelectrofocusing was performed in the first dimension and sodium dodecyl sulphate polyacrylamide gradient gel electrophoresis in the second. The charge differences behind the electrophoretic C4 polymorphism were shown to reside in the 95,000-u (atomic mass units) alpha-chain. Charge variation closely mirroring the alpha-chain differences were also found in a 49,000-u fragment of the alpha-chain, most probably C4d. The basic beta-chain could not be studied in detail, but no differences were observed with regard to molecular weight or charge of the gamma-chains of the different C4 gene products.

[Use of modern gene technology in forensic medicine]. / Anvendelse av moderne genteknologi i rettsmedisinsk arbeid.

Modern DNA technology has had a great impact upon the practice of forensic genetics. Recently developed methods have disclosed different types of genetic variability in human DNA. Typing of genetic DNA polymorphisms based on point mutations represents an alternative to the blood and protein systems developed before. However, the discovery of the so-called hypervariable regions (HVR) in the genome, which represent grossly rearranged areas of DNA, has, revolutionised the field. "Fingerprints", nearly specific for each individual in the population, can be developed by employing specific probes, restriction enzymes and Southern blot technique. We present some results of the application of these techniques in criminal cases investigated at the Institute of Forensic Medicine in Oslo. In future, the sensitivity of the methods may be increased through amplification procedures (PCR reaction).

GLO polymorphism in Norway.

GLO phenotype distribution and GLO allele frequencies in samples of the Norwegian population and the Lappish minority of Norway are presented. The GLO frequency is 0.442 in 216 Norwegians, while it is 0.304 in 184 Lapps; the difference is statistically significant. There are furthermore probably differences in gene frequencies between two main groups of Lapps.

ESD polymorphism in Norway.

ESD phenotype distribution and allele frequencies in 217 Norwegians and 196 Norwegian Lapps are presented. There is good accordance with Hardy-Weinberg distribution, ESD1 allele frequencies are 0.887 in the Norwegians and 0.872 in the Lapps.