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PubMed1999

Production and functional activity of a recombinant von Willebrand factor-A domain from human complement factor B.

Factor B is a five-domain 90 kDa serine protease proenzyme which is part of the human serum complement system. It binds to other complement proteins C3b and properdin, and is activated by the protease factor D. The fourth domain of factor B is homologous to the type A domain of von Willebrand Factor (vWF-A). A full-length human factor B cDNA clone was used to amplify the region encoding the vWF-A domain (amino acids 229-444 of factor B). A fusion protein expression system was then used to generate it in high yield in Escherichia coli, where thrombin cleavage was used to separate the vWF-A domain from its fusion protein partner. A second vWF-A domain with improved stability and solubility was created using a Cys(267)-->Ser mutation and a four-residue C-terminal extension of the first vWF-A domain. The recombinant domains were investigated by analytical gel filtration, sucrose density centrifugation and analytical ultracentrifugation, in order to show that both domains were monomeric and possessed compact structures that were consistent with known vWF-A crystal structures. This expression system and its characterization permitted the first investigation of the function of the isolated vWF-A domain. It was able to inhibit substantially the binding of (125)I-labelled factor B to immobilized C3b. This demonstrated both the presence of a C3b binding site in this portion of factor B and a ligand-binding property of the vWF-A domain. The site at which factor D cleaves factor B is close to the N-terminus of both recombinant vWF-A domains. Factor D was shown to cleave the vWF-A domain in the presence or absence of C3b, whereas the cleavage of intact factor B under the same conditions occurs only in the presence of C3b.

Amino Acid Sequence↗
PubMed1976

C3 metabolism in a patient with deficiency of the second component of complement (C2) and discoid lupus erythematosus.

A patient with a hereditary deficiency of the second component of complement and discoid lupus erythematosus with features of systemic lupus erythematosus was studied. The propositus had a 9-year history of rash and arthralgia. Transient renal disease had completely resolved; there was a history of seizures. Examination of his serum disclosed antinuclear antibodies but no total haemolytic complement activity. C2 was absent. Serum concentrations of C1s, C3, C5 and C9 were elevated; other complement components were present in normal concentration, including C3 pro-activator. The patient's C3 pro-activator was electrophoretically converted by inulin and four of five lipopolysaccharides, but was poorly converted by aggregated human IgG. Two separate turnover studies with radiolabelled C3 showed fractional catabolic rates of 3-03 and 2-48% of the remaining plasma pool/hr (range of three normals: 1-62-2-18%/hr); and estimated C3 synthetic rates of 2-74 and 2-31 mg/kg/hr (range of three normals: 0-89-1-40 mg/kg/hr). Serum complement profiles of the patient's family demonstrated that the C2 deficiency was inherited as an autosomal codominant. One sibling, homozygous for C2 deficiency, and three other siblings, both parents and one daughter, all heterozygous for C2 deficiency, are in good health. Immunofluorescent studies of the patient's diseased skin exhibited substantial deposits of IgG, IgM, C1q, and C4 but not of later acting complement components, properdin, or C3 proactivator. These studies do not support the notion that inflammation in C3-deficient individuals with lupus erythematosus is mediated by the alternative complement pathway.

Adult↗
PubMed1975

Binding of the complement intermediate C56 to zymosan in acute phase human sera.

C56 is known to appear in the fluid phase when zymosan is incubated at 37 degrees C with certain acute phase 'reactor' sera. In the present study, C56 was detected bound to the zymosan particle prior to its appearance free in solution. In reactor sera C56 was formed and released with kinetics similar to that of the generation and decay of a C56-binding site formed when zymosan was incubated with normal serum. Bound and fluid phase C56 was detected only in reactor sera, and was generated only by agents known preferentially to activate the properdin pathway. Elution of C56 from zymosan in hypertonic salt solutions proved to be a convenient step in the partial purification of large amounts of this haemolytically active bimolecular complex.

Binding Sites↗
PubMed1975

Immunoglobulin A nephropathy.

Of 475 renal biopsles examined by immunofluorescence, IgA was seen located selectively in the glomerular mesangium of 18 patients. These patients were generally young men and had hematuria, only minimal proteinuria, and normal renal function. Glomerular lesions consisted of focal segmental capillary hypercellularity or sclerosis and mesangial thickening due to an increase in mesangial cells, matrix, and electron-dense deposits. Both IgG and C3 were frequently seen with IgA in the mesangium as was properdin in five of six cases, but C4, a component of the classical pathway of complement activation, was seen only infrequently. Serum IgA levels were elevated in many patients, but serum complement components were normal. These findings suggest a possible unusual immune pathogenesis with local mesangial binding and alternate pathway activation of complement.

Adolescent↗
PubMed1975

[The complement system].

The complement system may be activated by at least two different pathways: the clinical pathway involving C1, C4 and C2 and the alternative pathway involving properdin, C3, factor B and factor D. The classical pathway can be activated by antigen antibody complexes, while the alternative pathway can be activated by other substances such as natural polysaccharides. Both pathways lead to an activation of C3 and of the last complement components (C5 to C9). Congenital defects of the complement system have been described for several components. Some of these defects are relatively well tolerated, but others, such as C3 deficiency, lead to increased susceptibility to bacterial infections. Acquired complement defects are frequently observed in association with several diseases. Usually they are characterized by an increased level of complement components involved in the classical pathway and therefore reflect activation by antigen antibody complexes. Such changes may be systematic, as in lupus erythematodes, or localized to some biological fluids such as synovial fluid in rheumatoid arthritis. In some renal diseases the complement profile suggests activation of the complement system by the alternative pathway, and this may reflect a different pathogenesis.

Angioedema↗
PubMed1992

[Intravenous immunoglobulin in the treatment of neonatal septicemia].

Thirty-seven neonates with confirmed septicemia through hemoculture were studied. Of them, 18 were treated with antibiotic and the other 19 were given 500 mg/kg of intravenous immunoglobin with a pH of 4.25 (IGIV). The greater part of the neonates in this study were full-term or near full-term. There were no differences in age, gestational age and weight, nor in mortality, the bacterias found and the clinical manifestations which were seen in both groups. Yet, the hospitalary stay was shorter for those in the group treated with IGIV (13.9 +/- 5.7 days) than in the trial group (24.4 +/- 10.3 days); as well as some clinical manifestations like diarrhea and splenomegalia (P < 0.05). The serum of the neonates from the IGIV group showed a greater capacity of opsonization and inhibition of bacterial growth than those in the trial group (P < 0.001), coinciding with an increase of 300 mg/dL in the serum levels of IgG of the group treated with IGIV from the 3rd day of the study and the C4 and B-Properdine factor serum levels from the 7th day of the study, while in the trial group, there were no changes in these factors (P < 0.001). Even though no differences were seen in the mortality rate due to septicemia, the results suggest a much shorter evolution of the illness in patients treated with IGIV. In addition, the serum of those patients treated with IGIV showed in in vitro studies, a better bacteriostatic activity and a better capacity to opsonize the bacterias isolated in the hemocultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteremia↗
PubMed1992

Primary structure of cobra complement component C3.

Complement component C3 is a multifunctional protein known to interact specifically with more than 10 different plasma proteins or cell surface receptors. Cobra venom contains cobra venom factor, a structural analogue of C3 that shares some properties with C3 (e.g., formation of a C3/C5 convertase) but differs in others (e.g., susceptibility to regulation by factors H and I). The elucidation of structural differences between C3 and cobra venom factor can be expected to help identify functionally important regions of C3 molecules. To that end we have undertaken the molecular cloning of both cobra C3 and cobra venom factor to take advantage of the unique biologic system where both proteins are produced by the same species. We report the primary structure of cobra C3 mRNA and the derived protein structure. Cobra C3 mRNA is 5211 bp in length. It contains an open reading frame of 4953 bp coding for a single pre-pro-C3 molecule, consisting of a 22-amino acid signal sequence, a 633-amino acid beta-chain (70 kDa), and a 992-amino acid alpha-chain (112 kDa) which is separated from the beta-chain by four arginine residues. There are no N-glycosylation sites in cobra C3. Cobra C3 exhibits approximately 58% nucleotide sequence identity with C3 from mammalian species. At the protein level, sequence identity is approximately 52% and sequence similarity approximately 71%. All 27 cysteine residues are highly conserved as are the C3 convertase cleavage site, the thioester site, and the factor B binding site. Cobra C3 also seems to have homologous binding sites for factor H and properdin, as well as a conserved sequence in the functionally important region of the C3a anaphylatoxin. The sequence homology at the CR2 and CR3 binding sites does not exceed the overall sequence homology. Accordingly, the existence of CR2 and CR3 binding sites can neither be deduced nor excluded.

Amino Acid Sequence↗
PubMed1992

[Characteristics of immunobiological resistance of children with diabetes mellitus].

Immunoglobulins and nonspecific defence factors (complement, properdin, lysozyme) were studied over time in 194 children suffering from diabetes mellitus. In 145 children, diabetes mellitus was associated with chronic tonsillitis. Resistance in 49 children was examined depending on the phase of diabetes mellitus. The data obtained indicate that diabetes mellitus is marked by imbalance of nonspecific defence factors and humoral immunity. These changes are obviously related to the disease gravity, phasic nature of the process, diabetes mellitus standing, and the presence of concomitant diseases. No parallelism was established between the level of nonspecific defence factors and specific immunity activity.

Adolescent↗
PubMedDate not supplied

Influence of genetic factors on the susceptibility to HBV infection, its clinical pictures, and responsiveness to HBV vaccination.

The association of genetic factors with hepatitis B virus (HBV) infection susceptibility, its different manifestations, and the different responses to hepatitis B antigen vaccination have been described by several authors. With regard to HLA class I molecules, association with HLA-B was especially observed.HLA-B35 and -B8 correlated with chronic active hepatitis (CAH)and with hepatitis B carriers. Correlation between HBV infection and HLA class II (loci DR and DQ)was also indicated, but results are not clear regarding the clinical pictures of the disease nor vaccination response. HLA class III (fourth complement component--C4,third complement component--C3, and properdin factor--BF) are associated with various manifestations of this disease. The gammaglobulin phenotype Gm (1,2,3,10,21)was more frequent in CAH. However, in only three publications was the impact of HLA on the efficacy of interferon therapy taken into account.

HLA Antigens↗
PubMed2005

[Dependence of some infectious diseases on genetic factors].

Association of genetics factors with several infectious diseases was presented. According to measles and rubella heritability indexes of specific humoral immunity for both sexes (twins method) and HLA system were described. At mumps infection except heritability index and HLA system, polymorphism of the third component of complement (C3), properdin system (BF) and immunoglobulin Gm and Km phenotypes results were presented. In patients with hepatitis A HLA system was touched. In relation to HIV/AIDS investigation were connected with HLA system and chemokine to HIV-1 receptor.

Communicable Diseases↗
PubMedDate not supplied

Bf S gene frequency in Nigerians with HIV infection.

Complement immunogenetic susceptibility to human immunodeficiency virus (HIV) infection was examined in 40 Nigerians with serological and/or clinical evidence of the infection. A mild increase in C4A null alleles (C4AQO) frequency was observed in the patient group compared to a group of healthy subjects (25 per cent vs 17 per cent) but overall the HIV infected and the reference groups did not differ significantly in the frequency of alleles of C4A or C4B. In contrast, properdin factor B (Bf) S gene frequency was significantly higher in the patients with HIV infection (p less than 0.025). There was a concomitant decrease in Bf F allele and gene frequencies (p less than 0.01, and p less than 0.05), respectively. Furthermore, blank Bf allotypes due to excessive complement consumption were detected in two asymptomatic patients. These findings suggest that Major Histocompatibility Complex (MHC) located complement genes may be important HIV infection. In particular Bf S gene or even C4AQO alleles may be permissive or influence outcome of infection with HIV.

Adult↗
PubMed1991

[The determination of specific proteins in the biological fluids from pregnant women suffering from diabetes mellitus].

An immunochemistry analyser has been used in testing a series of specific proteins (complement components C3 and C4, properdin, factor B, immunoglobulins G, M and A, alpha 1-antitrypsin, alpha 1-acid protein and alpha 2-macroglobulin) in biological fluids of normal and diabetic women in third-trimester pregnancy. Significant abnormalities in the protein spectrum were found in diabetes mellitus, a marker to be used in monitoring of diabetic pregnancies and control of therapy.

Amniotic Fluid↗
PubMed1991

[Occurrence of complement defects in meningococcal disease: who should be examined?].

Congenital complement deficiency states occur very rarely. These deficiencies are associated with a high risk of meningococcal disease (MD). We suggest that the following groups of individuals with MD are examined for complement deficiencies: 1. Individuals belonging to families, in which more than one case of MD has occurred with an interval exceeding one month. 2. Individuals infected with the low-virulent meningococcal serogroups W-135, 29E, X, Y, Z. 3. Individuals with recurrent MD. Since properdin deficiency probably is the most common deficiency associated with MD it is important that the screening includes the alternative complement pathway.

Complement System Proteins↗
PubMed1991

Human IgA1 blockade of IgG-initiated lysis of Neisseria meningitidis is a function of antigen-binding fragment binding to the polysaccharide capsule.

We have recently shown that human IgA1 can initiate lysis of group C Neisseria meningitidis via the classical C pathway when bound to specific outer membrane proteins, but that IgA1 can also function as a blocking antibody when bound to the polysaccharide capsule of meningococci. In this report, we further characterized IgA1 blockade by examining the effect of IgA1 on IgG-initiated immune lysis of group C meningococci. We purified IgG and monomeric IgA1 from either convalescent group C meningococcal case sera or tetravalent (A, C, Y, W135) polysaccharide vaccinate sera. In the absence of IgA1, IgG initiated complete lysis (greater than 99%) of strains 118V (C:P3,4:L2,4) 126E (C:P3:L1,8), and 35E (C:P5:L2). Addition of IgA1 to the bactericidal reaction mixture completely blocked the lytic function of IgG. Removal of the Fc portion of IgA1 with either pepsin or IgA1 protease did not affect blockade. Both the F(ab')2 and Fab derivatives of IgA1 blocked lysis quantitatively as well as intact IgA1. The Fc fragment produced by IgA1 protease cleavage neither increased nor decreased Fab-mediated blockade. IgA1 and its Fab and F(ab')2 fragments blocked IgG-initiated lysis via either the classical pathway in factor B-depleted and in properdin-deficient serum, the alternative pathway in MgEGTA-chelated serum, or both pathways combined. Absorption of the IgA1 and IgG with alum-bound group C polysaccharide completely removed blocking and lytic activity, respectively, indicating that both the blocking IgA1 and the lytic IgG were specific for the group C capsule. Blocking by IgA1 was a linear function of the polysaccharide Ag-binding capacity (ABC) ratio of blocking IgA1 to lytic IgG. Complete blockade was observed at an ABC ratio of 5.5. At ABC ratios of 3.3 and 4.4, IgA1 affected significant blockade whether added previous to, concurrent with, or subsequent to sensitization of the organisms with IgG. With the use of a C polysaccharide ELISA, we found that the binding of IgA1 to the group C capsule in the presence of IgG exhibited positive cooperativity and therefore that blockade was independent of the ability of IgA1 to directly compete with IgG for binding to epitopes within the group C capsule. We conclude that IgA1, when bound to the group C polysaccharide capsule, can block IgG-initiated lysis of group C meningococci through either the classical or the alternative pathway before or after the organism is exposed to IgG, and that blockade is an Fc-independent event.

Antibodies, Bacterial↗
PubMed1991

[Levels of immunoglobulins in various media from healthy pregnant women and women with diabetes mellitus and EPH gestosis].

The introduction deals with of the history, etiology and, briefly, clinical manifestations of endemic nephropathy. The authors state that a large number of investigations have been done until today, but without producing a diagnostic test for early diagnosis of the disease. This led the authors to pursue certain laboratory investigations. The control group consisted of 30 healthy individuals while patients diagnosed as Endemic Nephropathy were grouped according to stages of the disease: initial, developed, terminal stages. Nucleotides in erythrocytes (5' UMP, 5' IMP, 5' GMP, 5,CMP, 5' AMP, 5' ADP, 5' ATP) were determined on the Acidic Aminoanalyzer, with use of a special UV detector. Catecholamines in the urine were determined by using ratiofluorometery. Creatinine phosphocinase, hydroxybutirat--dehydrogenase and 2,3 DPG were determined on the "Carlbiochem" enzymometer. LDH, its isoenzymes as well as its profile were determined by electrophoresis on starch gel. Specific proteins such as haptoglobin, alpha 2 macroglobulin, alpha 1 antitrypsin, alpha 1 acid glycoprotein, properdin factor B, ceruloplasmin were determined on the Immunochemistry Analyzer. Total cholesterol and cholesterol in lipoproteins fractions VLDL, LDL and HDL were determined on the Cholesterol Analyzer. All results were evaluated statistically. Our conclusion is that they are interesting and contribute to the diagnosis of endemic nephropathy.

Adult↗
PubMed1990

Red cell enzyme and serum protein polymorphisms in the western Cape region of South Africa.

Nine red cell enzyme systems: Acid phosphatase-1 (ACP1), adenosine deaminase (ADA), adenylate kinase-1 (AK1), esterase D (ESD), 6-phosphogluconate dehydrogenase (PGD), phosphoglucomutase first and second loci (PGM1, PGM2), carbonic anhydrase-2 (CA2) and glyoxalase-I (GLO1); and three serum protein systems: haptoglobin (HP), transferrin (TF) and properdin factor B (BF), were examined in four populations--Caucasoids, "Cape Coloureds", Cape Malays and Negroes--in the western Cape region of South Africa. The results show distinct differences between the four groups for several genetic markers.

Black People↗
PubMed1978

Activation of the alternative pathway of complement by Entamoeba histolytica.

A cytopathogenic effect was observed when Entamoeba histolytica was exposed to human sera from individuals with no clinical history or laboratory evidence of amoebiasis. Absorption studies showed that the effect was not due to natural antibodies. Studies performed using ethylenediamine tetracetic acid (EDTA), cobra venom factor (CoF) and heat-inactivation at 56 degrees C, indicated that the cytopathogenic effect was complement dependent. Furthermore, by using ethylene glycol tetracetic acid (EGTA) and Mg++, zymosan, heat-inactivation at 50 degrees C to destroy the activity of factor B of the alternative pathway, as well as electrophoretic studies with anti-human factor B, it was possible to determine that E. histolytica activated the properdin pathway. Finally, complement determinations indicated that incubation of E. histolytica with normal human serum consumed complement. The diminution in CH50 correlated with a consumption of C3 but not of C1, C4 and C2. It was concluded from these results that trophozoites of E. histolytica activate the alternative pathway of the human complement system.

Animals↗
PubMed1979

The effect of interferon induction on complement level in rat.

Relatively high levels of interferon were achieved in rat sera by intracardial inoculation with Sindbis virus followed 15 min later by intraperitoneal application of dimethylsulfoxide. At intervals when interferon titres reached the maximum, the levels of complement were decreased as compared with the control group of rats. Single administration of dimethylsulfoxide did neither induce interferon nor influence the complement levels in sera of rats of the Dobrá Voda breed tested. Similar results were obtained with concentrated Newcastle disease virus inoculated intraperitoneally. Of interest is the finding that properdin levels seem to increase at the same time as interferon.

Animals↗