C7 deficiency, abnormal platelet aggregation, and rheumatoid arthritis.
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Arthritis, Rheumatoid↗
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Results for “Complement C7”
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Functional identification of serum complement components following electrophoresis in polyacrylamide gels containing sodium dodecyl sulphate.
A method is described for detecting the active complement components C6 and C7 after polyacrylamide gel electrophoresis (PAGE) of whole serum in the presence of sodium dodecyl sulphate (SDS). The method involves the removal of SDS by washing with non-ionic detergent followed by the application of an erythrocyte/agarose gel to detect haemolytic activity. Two forms of human C6 with apparent molecular weights of approximately 121,000 daltons and 114,000 daltons were observed. Major activity resided in the 121,000 dalton species. The 2 forms of human C6 were not related to known genetic polymorphisms for this component. Analysis of sera from different animal species showed that not all possessed the 2 forms of C6 and that there were interspecies differences in C6 molecular weights. These are most marked in the case of human and murine C6; the major form of murine C6 had a molecular weight approximately 20,000 daltons less than the major human form. One form of human C7 with an apparent molecular weight of 104,000 daltons was seen. The molecular weights of C7 from the various animal sera tested did not differ significantly from this. Studies with reducing agents and metabolic inhibitors showed that both C6 and C7 required intact disulphide bonds and sulphydral groups for functional activity.
Animals↗
Elucidation of the disulfide-bonding pattern in the factor I modules of the sixth component (C6) of human complement.
Complement component C6 is known to contain two factor I modules in tandem at its C-terminus. To localize the disulfide bridges in those domains, native C6 was cleaved with trypsin, followed by subtilisin. The resulting digests were separated by reversed-phase HPLC, and all of the potential cystine-containing fragments were detected by a fluorescence assay and amino acid composition analyses. Final identification of the disulfide bonds was achieved by Edman degradation of the corresponding peptides. From the data gained a 1-3, 2-9, 4-7, 5-10, 6-8 pattern was determined (Cys752-Cys802, Cys763-Cys780, Cys765-Cys816, Cys772-Cys795, Cys841-Cys852, Cys846-Cys898, Cys859-Cys876, Cys861-Cys911, Cys867-Cys891). These findings are compared with the strongly related complement components C7 and factor I.
Amino Acid Sequence↗
[C7 typing of blood stains using isoelectric focusing and immunoblotting].
By means of isoelectric focusing and immunoblotting C7 types were clearly demonstrated from bloodstains which had been stored at 37 degrees C for up to three weeks, at room temperature for up to six weeks and at 4 degrees C for over ten weeks. The C7 typing is practically useful in medicolegal individualization of unknown bloodstains.
Alleles↗
Inherited structural variation and linkage relationships of C7.
Three structural forms of C7 have been distinguished by isoelectric focusing. They are the products of three co-dominantly expressed alleles at an autosomal locus. The C7 locus is close to that for C6, but is not close to the HLA complex.
Alleles↗
Polymorphisms of serum proteins in Japanese patients with vascular diseases. I. Factor XIIIB, plasminogen and complement types in primary varicose veins.
The polymorphisms of the B subunit of coagulation factor XIII (F13B), plasminogen (PLG), complement C6, C7, factor B (BF) and factor I (IF) were studied among 21 unrelated Japanese patients with primary varicose veins (PVV) by isoelectric focusing followed by immunoblotting. The allele frequencies for F13B*2 and IF*A in PVV patients were significantly higher (F13B*2, p = 0.0047; IF*A, p = 0.0006) than those in healthy controls (n = 60). Significant associations of F13B 2 allotype [p = 0.0220, relative risk (RR) = 13.9] and IF A allotype (p = 0.0006, RR = 10.0) with PVV were observed; however, no significant association of PLG, C6, C7 or BF allotype with the disease was found.
Adult↗
C7 deficiency and persistent haematuria.
A 14-year-old boy had persistent haematuria along with complete C7 deficiency. No significant changes in glomeruli and tubules were found in a renal biopsy specimen by light microscopy and immunofluorescence gave negative results for immune deposits. Electron microscopic examination demonstrated an attenuation of the glomerular capillary basement membrane without lamination and a diagnosis of thin basement membrane disease was made. It would be difficult to conclude that patients with C7 deficiency were predisposed to develop glomerulonephritis caused by immunologic aberrations. A family study failed to provide evidence of an association of C7 deficiency and thin basement membrane disease.
Adolescent↗
Independent and consecutive action of the complement components C5, C6 and C7 in immune hemolysis. I. Preparation of EAC1-5 with purified guinea pig C3 and C5.
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Animals↗
C7 reference typing and nomenclature recommendations.
The results of reference typing for C7 are presented and discussed. It appears that the present literature is using consistent nomenclature except that it was not possible to distinguish between the European C7-3 allele and Japanese C7-6. Oriental populations have both a higher frequency of variants and a greater variety of variants than Caucasian populations. Some samples with complex patterns defied classification, and it is speculated that these may be from persons with duplicated C7 genes. It is recommended that no change to the present system of nomenclature be made before a more detailed molecular understanding of the system is achieved.
Complement C7↗
Increased levels of soluble complement receptor 1 in serum patients with liver diseases.
Complement receptor type 1 (CR1) is an integral membrane protein of many hematopoietic cells and is found in a soluble form in plasma. Preliminary data have indicated that soluble complement receptor 1 (sCR1) levels in serum were increased in patients with cirrhosis. In this study, sCR1 was measured in patients with various liver diseases with a newly established enzyme-linked immunosorbent assay (ELISA). sCR1 level was elevated in chronic active hepatitis C (24 patients, 62.6 +/- 31 ng/ML; 31 normal controls, 31.4 +/- 7.8 ng/mL, P < .001), and in cirrhosis (35 patients, 143.7 +/- 61 ng/mL, P < .001). The levels increased transiently in 3 patients who had amanita phalloides intoxication. In 25 patients with advanced cirrhosis (pretransplantation screening), there were significant inverse correlations between sCR1 and both the prothrombin index (rs = -.60, P < .002) and the aminopyrine breath test (rs = -.51, P < .01). Following liver transplantation, the levels dropped from 166 +/- 70 to 49 +/- 24 ng/mL (P < .0001), and serial measurements in the posttransplantation period showed a correlation with liver dysfunction, regardless of etiology. Since CR1 is not produced by hepatocytes, the most likely explanation for the increased level of sCR1 is reduced is reduced catabolism. Thus, sCR1 may be added to the short list of large glycoproteins that accumulate in liver disease.
Amanita↗
Studies on the seventh component of complement: the mode of action of C7.
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Animals↗
The molecular architecture of human complement component C6.
The molecular architecture of human complement component C6 was elucidated at several levels of structural organization. The entire primary structure of C6 was determined by sequencing C6 cDNA that was cloned from a human liver lambda gt11 library. The polypeptide chain of C6 contains 913 amino acids. The protein is homologous with the other terminal components of complement, C7-C9. Specifically, C6 has 29% of its residues identical with C7, and 55 of the 56 cysteines found in C7 match those in C6. The C6 polypeptide chain is cross-linked by 32 disulfide bonds, and most of the cysteines are located in short (34-77 amino acids) discrete segments that exhibit homology with a wide variety of other proteins such as thrombospondin, the low density lipoprotein receptor, epidermal growth factor, and complement factors H and I. C6 is a glycoprotein, and it has two oligosaccharide groups attached to asparagines located near the amino and the carboxyl termini of the molecule. The organization of secondary structural elements in C6 was elucidated using circular dichroism spectroscopy and an empirical method based on sequence analysis. C6 has an estimated 12% alpha-helix, but is comparatively richer in beta-sheet (29%) and beta-turns (21%). Most of the predicted alpha-helical structure resides in a portion of the polypeptide chain that is free of cysteine and which shares homology with C9 and perforin. The tertiary structure of the C6 molecule was visualized by transmission electron microscopy; it has a sickle shape with dimensions of 144 x 66 A. The combined results are discussed and comparisons made with the other late acting components of complement and perforin.
Amino Acid Sequence↗
Combined genetic deficiency of C6 and C7 in man.
By routine screening of sera, a subject was discovered who showed a sub-total deficiency of C6 and C7. No clinical disease was associated with this deficiency which was transmitted through the subject's family as a single genetic characteristic, the C6 deficiency being associated with a silent allele at the structural locus. The propositus was found to have low quantities of an abnormal C6 which was both antigenically deficient and smaller in size than normal C6 (110,000 daltons compared with 140,000 daltons) and small quantities of apparently normal C7. It is concluded that the most likely explanation for this defect is that the subject has a structural mutation in his C6 gene which produces hyopsynthesis not only of C6 but also of the closely linked gene for C7. These findings suggest the possibility that C6 and C7 may function as a single genetic unit and that the primary transcript copied from the genome includes information for both proteins.
Aged↗
Double replica electroblotting for the simultaneous phenotyping of C6 and C7, and its application to the examination of bloodstains.
A new reliable and reproducible technique for the simultaneous determination of C6 and C7 types is presented, which employs double replica electroblotting after isoelectric focusing. It permitted clear discrimination of both C6 and C7 components, and the patterns were nearly comparable to those demonstrated separately. The population data obtained by this new technique fitted the genetic hypothesis. The present double replica electroblotting method was successfully applied to the combined phenotyping of C6 and C7 from bloodstains which were stored at room temperature for up to 4 weeks. The method is quite suitable for medicolegal examination of bloodstains particularly for the saving in the amount of sample.
Blood Stains↗
The SC5b-7 complex: formation, isolation, properties, and subunit composition.
Activation of C in C8-depleted serum results in the formation of a soluble complex containing C5, C6, and C7. The complex has an electrophoretic mobility of an alpha-globulin, an s-rate of 18.5S, and a m.w. of 668,000 daltons. This complex was isolated and upon SDS polyacrylamide gel electrophoresis it was found to contain, in addition to C5b, C6 and C7, an 88,000 dalton glycoprotein. The protein was identified as the band V protein of the soluble C5b-9 complex. It is referred to as SIIIs-protein, or S-protein. Since the S-protein does not bind to C5b-6, it is concluded that it is incorporated during the fusion of C5b-6 with C7. The SC5b-7 complex exhibits the same neoantigen as the SC5b-9 complex, but compared to the C5b-6 complex it appears to contain an additionally qualitatively distinct neoantigen.
Animals↗
Complement deficiency predisposes for meningitis due to nongroupable meningococci and Neisseria-related bacteria.
Nongroupable meningococci or bacteria related to the genus Neisseria rarely cause meningitis. Complement deficiency has been identified as a major predisposing factor for meningococcal disease. To assess whether patients with meningitis due to such strains have a complement deficiency, we studied 12 persons. Six patients had meningitis due to nongroupable strains of meningococci, and six patients had meningitis due to Moraxella species or Acinetobacter species. Inherited complement component C7 or C8 deficiency was found in two persons who had had meningitis due to nongroupable meningococci, and one C8-deficient person had had meningitis caused by Moraxella osloensis. Hypocomplementemia resulting from CSF drain-associated shunt nephritis was found in one person with meningitis due to Moraxella nonliquefaciens and in one person with meningitis due to Acinetobacter lwoffi. This rather high frequency of inherited or acquired complement deficiencies among patients with meningitis due to nongroupable meningococci, Moraxella species, and Acinetobacter species justifies the recommendation that such patients must be studied for complement deficiency.
Acinetobacter Infections↗
A study of complement components C3, C5, C6, C7, C8 and C9 in chronic membranoproliferative glomerulonephritis, systemic lupus erythematosus, poststreptococcal nephritis, idiopathic nephrotic syndrome and anaphylactoid purpura.
In a comparative study the hemolytic activity of C3, C5, C6, C7, C8, C9 and the C3 proactivator (C3PA) were measured in sera of 22 patients with chronic membrano-proliferative glomerulonephritis (CMPGN), 15 patients with idiopathic nephrotic syndrome, 10 patients with systemic lupus erythematosus, 7 patients with anaphylactoid purpura and 10 patients with acute poststreptococcal nephritis. In CMPGN, C3, C5, C6, C7 and C8 were low in the majority of the patients, whereas C9 and C3PA were depressed only in 21% and 11% of the patients, respectively. By contrast, C3PA and C8 showed striking depressions in the idiopathic nephrotic syndrome. In lupus erythematosus, all the C factors, including C3PA were found to be low with the exception of C9, which was normal in 80% of the patients studied. C3, C5, C6 and C7 were found to be depressed in acute glomerulonephritis; C8 and C9 titers were normal. In all patients studied with anaphylactoid purpura, CH50 and C3 titers were elevated markedly.
Adolescent↗
Molecular bases of combined subtotal deficiencies of C6 and C7: their effects in combination with other C6 and C7 deficiencies.
Combined subtotal deficiency of C6 and C7, in which both proteins are expressed at very low levels, has been observed in homozygous form in two families. A defect at the 5' splice donor site of intron 15 of the C6 gene explains the low molecular weight of the C6 protein and is probably responsible for its low expressed concentration. The C7 defect is more enigmatic: the protein is of normal molecular weight, low circulating concentration, and altered isoelectric point. An Arg > Ser codon substitution in exon 11 is the only molecular alteration within the mature C7 protein. These defects are associated with a characteristic set of polymorphic DNA markers in the C6/C7 region, forming a distinct haplotype. The haplotype has been found in combination with a number of other haplotypes containing defective genes that lead either to C6 or C7 deficiency, but with different consequences. Where it is combined with a C6-deficient gene, the serum C7 levels can be surprisingly high, possibly because there is no C6 generating C56 to consume the C7. In contrast, where the C7 genes are both defective (but still partially functional), there may be a profound deficit of circulating C7 because there is ample C6 to produce C56 and consume the already small amount of C7. Each molecular defect has also been found in isolation and has the expected effect.
Amino Acid Sequence↗