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PubMed1987

Immunoprotective murine monoclonal antibodies specific for the outer-core polysaccharide and for the O-antigen of Escherichia coli 0111:B4 lipopolysaccharide (LPS).

The antigen specificity of two immunoprotective monoclonal antibodies derived from mice immunized with Escherichia coli 0111:B4 bacteria and boosted with purified lipopolysaccharide (LPS) were investigated. One of the antibodies, B7, was shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunostaining to bind to the O-antigen containing LPS species, whereas the other antibody, 5B10, reacted with both O-antigen containing homologs and the O-antigen-deficient LPS. 5B10 did not bind to LPS from E. coli J5, an Rc mutant of E. coli 0111:B4 that lacks both the O-antigen and outer core sugars. 5B10 did not cross-react with LPS from several other E. coli strains. Thus 5B10 appeared to recognize a type-specific epitope in the outer core of LPS exclusive of Rc determinants. The monoclonal antibody specific for the polymeric O-antigen is of the IgG3 subclass, and the monoclonal antibody 5B10 specific for the outer core of LPS is an IgG2a. Although B7 and 5B10 were equally able to protect mice from a lethal challenge of E. coli 0111:B4 organisms, the outer core-specific IgG2a antibody was much more efficient at mediating the binding of human complement C3 than the O-antigen-specific IgG3 monoclonal antibody.

Animals↗

PubMed1988

The phagocytic activity of Lumbricus terrestris leukocytes is enhanced by the vertebrate opsonins: IgG and complement C3b fragment.

The effect of the vertebrates opsonins: IgG and complement C3 fragments on phagocytic activity of Lumbricus terrestris leukocytes towards sheep erythrocytes was studied. Sheep erythrocytes were previously sensitized with specific IgG or IgM and coated with one of the third component fragments (C3b, C3bi, C3d) of human complement. Our results show that leukocyte phagocytosis was enhanced by vertebrate IgG and C3b complement fragments but not by IgM and fragment C3d. Because opsonization in vertebrates is related to the presence of receptors on the surface of phagocyte membrane, our results suggest that similar receptors exist on earthworm leukocyte surfaces. These new data strengthen the arguments in favour of the presence of components in Lumbricus terrestris which partially share common structures and functions with components of vertebrate humoral immune reactions.

Animals↗

PubMedDate not supplied

[Primary chronic polyarthritis with kidney involvement (mesangiocapillary glomerulonephritis)].

A 34 year old white male patient suffering from seropositive "probable" rheumatoid arthritis developed a severe hypocomplementemic mesangiocapillary glomerulo-nephritis. Rheumatoid factors (Latex test, Waaler-Rose titer) and IgM were markedly elevated in the serum. The third component of complement (C3) was markedly depressed, while the fourth component (C4) was within normal range. The rapid progression of the disease forced us to start an immunosuppressive drug therapy using azathioprine and steroids. Despite marked clinical improvement, e.g. normalisation of complement components, renal function, the disappearance of rheumatoid factor and proteinuria, the second biopsy taken two years later showed unchanged histological and immuno-histological changes of the glomerula.

Adult↗

PubMed1980

Leukopenia, hypoxia, and complement function with different hemodialysis membranes.

Complement activation during exposure of plasma to cuprophan has been postulated to cause leukopenia and hypoxia in hemodialysis patients. To determine if hypoxia is related to leukopenia and if complement activation leads to a depletion of functional complement components, we dialyzed four patients three times sequentially against each of four types of membranes: cuprophan, regenerated cellulose, cellulose acetate, and polyacrilonitrile. Within 20 min there was a marked leukopenia with cuprophan from 5541 +/- 376 to 1216 +/- 94 (P less than 0.001) and with regenerated cellulose from 5541 +/- 411 to 1533 +/- 203 (P less than 0.001). With cellulose acetate, the change from 5558 +/- 400 to 3783 +/- 341 (P less than 0.001) was less dramatic, and with polyacrilonitrile the fall from 5591 +/- 381 to 464 +/- 401 (P less than 0.02) was minimal. After 2 and 4 hours of dialysis, a rebound leukocytosis was seen with cuprophan, regenerated cellulose, and cellulose acetate, but not with polyacrilonitrile. Transient thrombocytopenia occurred with cuprophan and regenerated cellulose. In spite of the variable degree of leukopenia, all membranes induced a similar and significant hypoxia, which was progressive throughout dialysis, even during the rebound leukocytosis. After 4 hours, the mean PO2 ranged from 91 to 93 mm Hg with all membranes. Functional hemolytic titers of whole complement, C3, C5, and C4 were normal prior to hemodialysis and failed to decrease after 4 hours with any membrane. It is concluded that hemodialysis leukopenia is membrane-dependent and is not the cause of hypoxia. In addition, hemodialysis complement activation does not lead to functional complement depletion and is of no clinical significance.

Adult↗

PubMed1992

A long-term immunological study of childhood onset systemic lupus erythematosus.

Immunological dysregulation is an important cause of the development of systemic lupus erythematosus (SLE). Serological evaluation has been useful in the clinical management of patients and as a prognostic indicator. Sixteen patients who developed SLE as children were followed up for more than three years and immunological data collected. The results showed that (a) complement C3 concentration was lower in the active stage of SLE, especially during a major clinical exacerbation, but rarely preceded a major flare up. The concentration was often normal during the mildly to moderately active stage. In contrast, a low complement C4 concentration often preceded a major clinical exacerbation and could be of longer duration, sometimes persisting regardless of disease activity. (b) A T cell subset distribution study showed persistently low CD4 positive T cells in the peripheral blood of patients with SLE during the long term follow up, strongly suggesting that the intrinsic defect is mainly localised in T helper/inducer cells. These abnormal cellular defects did not tend to return to normal even in long term remission. (c) The persistently higher serum interleukin 2 and interleukin 2 receptor concentrations in SLE strongly suggested that the T cells were preactivated in vivo and that these phenomena might persist even in remission. (d) The best single parameter for predicting active SLE was anti-dsDNA. It was highly correlated with disease activity in most patients, and the asymptomatic increase of anti-dsDNA (greater than or equal to 60 U/ml, radioimmunoassay) was often followed by a major clinical exacerbation, especially in patients with a simultaneously low complement C4 concentration, suggesting that it might be an important warning sign of a major flare up. High dose steroids are indicated in this group of patients.

Adolescent↗

PubMed1975

Antibodies reacting with the glomerular mesangium. Isolation and immunopathology.

Antigens of porcine lung were prepared by homogenization and ultrasonic treatment of lung tissue. The antigens were digested by collagenase and trypsin and chromatographed on Sephadex G 200. After immunization of rabbits with certain fractions of the chromatographed material, antibodies could be obtained in rabbits which fixed in vitro and in vivo in the glomerular mesangium of rats, hogs and the human, but not in the basement membrane of glomeruli of these species. Following intravenous injection into rats, the antibodies could be observed in the mesangial area without an apparent loss of antigenicity for 55 days. While 5 days after the application of 20 mg of the anti-mesangial IgG-preparation, there were no glomerular changes histologically demonstrable, after 55 days small amounts of rat-IgG could be demonstrated histochemically within the mesangium. Deposits of rat-complement (C3) could not be demonstrated with certainty. Severe morphological lesions were absent. Rats injected with the same doses of antibody and simultaneously immunized with rabbit-IgG showed a substantially greater deposit of autologous rat-IgG and rat-complement within the mesangial area after 55 days. By histological examination focal and segmental scleroses of the mesangium were determined. A significant pathological proteinuria did not occur. The present model constitutes a new possibility for studying the function of the glomerular mesangium.

Animals↗

PubMed1996

Genetic markers associated with high versus low performance on episodic memory tasks.

Associations were studied between six serum protein polymorphisms (C3, BF, HP, ORM, TF, and GC) and high versus low scoring on episodic memory tasks in an attempt to identify QTL (quantitative trait loci) contributing to the heritability of this quantitative trait. Since a highly significant sex difference (p = .00002) was found with respect to the distribution of high and low scoring, with men showing a poorer performance, associations were studied separately for males and females. In females significant differences (p < .05) between the high and the low groups were found in four of six marker systems (C3, HP, TF, and CG), whereas in males a significant difference was found only in the HP system. Significant differences from population frequencies were also found more frequently in females than in males. The strongest marker associations were found with complement C3 and the acute-phase reactant HP, which suggests that immune response factors may be of importance in preserving episodic memory function. The overall results appear to indicate that episodic memory is a multifactorial and heritable quantitative trait where sex is an important determinant.

Adult↗

PubMedDate not supplied

Clinical significance of serum thrombomodulin levels in patients with systemic rheumatic diseases.

OBJECTIVE: To determine the soluble thrombomodulin (TM) level in the sera of patients with systemic rheumatic diseases and to analyze its relationship with clinical and laboratory parameters in patients with systemic lupus erythematosus (SLE). METHODS: Serum levels of TM were measured by an enzyme-linked immunosorbent assay in 124 patients with SLE and in 237 patients with systemic rheumatic diseases other than SLE. RESULTS: The frequency of patients with high TM levels (> or = 4.5 FU/ml) was 21% in SLE, 16% in rheumatoid arthritis (RA), 12% in Sjögren's syndrome (SS), and 4% in systemic sclerosis (SSc). The TM levels were significantly higher in SLE patients with the following abnormalities in their past history or present illness: persistent proteinuria, cellular casts, positive anti-dsDNA antibodies (p < 0.001), hypoalbuminemia, decreased creatinine clearance (Ccr), positive anti-Sm antibody, positive immune complex, leukopenia (p < 0.01), pericarditis, oral ulcer, fluorescent anti-nuclear antibody (FANA), decreased C3 and arthralgia (p < 0.05). The serum TM levels in SLE showed a direct correlation with the urinary protein level (p < 0.01) and serum creatinine level (p < 0.01), and an inverse correlation with the serum albumin level (p < 0.01) and complement C3 level (p < 0.05). In SLE patients with active disease, the median TM level at the time of admission (5.9 FU/ml) was significantly higher than at 6 months before admission (3.8 FU/ml, p < 0.01) and at 6 months after admission (4.2 FU/ml, p < 0.001). Moreover, elevation and reduction of the TM level in lupus patients with active disease parallelled that of the SLE disease activity index (SLEDAI). In two representative SLE cases, one with lupus nephritis (LN) and the other with thrombocytopenia without LN, elevated TM levels at disease flare were reduced along with the amelioration of the disease by administration of corticosteroids. CONCLUSIONS: The serum TM level is closely associated with SLE activity and appears to be useful as a new disease activity parameter of SLE.

Adult↗

PubMed1982

Ligand binding specificity of a rabbit alveolar macrophage receptor for C3b.

We have recently reported the isolation from rabbit alveolar macrophages of a receptor which retained its ligand-binding activity for the third component of complement (C3) and for its major proteolytic derived activation fragment (C3b). The isolated receptor demonstrated a greater ability to bind C3b than an equimolar amount of C3. C3b differs from C3 in at least two ways: it is a proteolytic cleavage product of C3 and it lacks the internal thiolester bond of C3. We have analyzed the binding ability to isolated receptor to various C3 and C3b analogs and we demonstrate that the specificity of the C3b-C3b receptor interaction depends upon the lysis of the C3 thiolester bond and accompanying conformational change rather than upon proteolytic cleavage of the C3 molecule. Minimal, if any, binding of C3 with an intact thiolester bond to the isolated receptor was demonstrable.

Animals↗

PubMed2006

Crystallization and X-ray diffraction analysis of the complement component-3 (C3) inhibitory domain of Efb from Staphylococcus aureus.

The extracellular fibrinogen-binding protein (Efb) of Staphylococcus aureus is a multifunctional virulence factor capable of potent inhibition of complement component-3 (C3) activity in addition to its previously described fibrinogen-binding properties. A truncated recombinant form of Efb (Efb-C) that binds C3 has been overexpressed and purified and has been crystallized using the hanging-drop vapor-diffusion technique. Crystals of native Efb-C grew in the tetragonal space group P4(3) (unit-cell parameters a = b = 59.53, c = 46.63 A) with two molecules in the asymmetric unit and diffracted well beyond 1.25 A limiting Bragg spacing. To facilitate de novo phasing of the Efb-C crystals, two independent site-directed mutants were engineered in which either residue Ile112 or Val140 was replaced with methionine and crystals isomorphous to those of native Efb-C were reproduced using a seleno-L-methionine-labeled form of each mutant protein. Multiwavelength anomalous diffraction (MAD) data were collected on both mutants and analyzed for their phasing power toward solution and refinement of a high-resolution Efb-C crystal structure.

Bacterial Proteins↗

PubMed1988

Absence of complement receptor type 3 and lymphocyte function antigen 1 causing deficient phagocyte and lymphocyte functions.

We describe a patient with delayed umbilical cord detachment, recurrent bacterial infections, and inability to form pus, despite persistent leucocytosis. Immunofluorescence studies with specific monoclonal antibodies showed a severe deficiency in the expression of alpha-chains of the receptor for the C3bi fragment of C3, complement receptor type 3, and the lymphocyte function antigen 1 molecule, found on neutrophil, monocyte and lymphocyte membranes. These membrane antigen defects were responsible for abnormalities in adhesive cell functions. Polymorphonuclear leucocytes demonstrated a markedly reduced chemiluminescence response as well as an impaired nitroblue tetrazolium test and superoxide generation to a particulate stimulus (zymosan), while the responses to a soluble stimulus (phorbol myristate acetate) were normal. In addition, random migration und chemotactic response to zymosan-activated serum were impaired. The lymphocytes demonstrated abolished natural killer cell cytotoxicity as well as abnormal humoral immunity and a lack of antibody response to pertussis and tetanus antigens.

Antigens, Differentiation↗

PubMed1972

Inactivator of the third component of complement as an inhibitor in the properdin pathway.

Evidence has been obtained that a single protein, known to modulate classical complement activation, also acts as an inhibitor in the properdin or alternate complement pathway. A highly purified inactivator of the third component of complement (C3) from human serum inhibited the proteolysis of Factor B in the properdin system (glycine-rich beta-glycoprotein) by glycine-rich beta-glycoproteinase. The inhibition was by the enzymatic destruction of glycine-rich beta-glycoproteinase activity. The major fragment of C3, C3b, which is the only known substrate of the C3 inactivator, blocked the destruction of glycine-rich beta-glycoproteinase by the C3 inactivator. Thus, in its inhibition of the porperdin pathway, the C3 inactivator destroys both the active form of glycine-rich beta-glycoproteinase and a protein involved in the conversion of the zymogen form of this enzyme (proglycine-rich beta-glycoproteinase) to its active form. The increased susceptibility to infections in a patient homozygous for deficiency of the C3 inactivator demonstrates the biologic significance of this protein.

Adult↗

PubMed1990

Hereditary angioedema: diagnosis and management.

Hereditary angioedema is a rare autosomal dominant disorder due to the deficiency of functionally active C1-inhibitor. It is characterised by recurrent episodes of subcutaneous and mucosal edema. We report a case of hereditary angioedema presenting with the classic features of recurrent swelling of the extremities, abdominal pain and laryngeal edema. Serum complement C3 level was normal but C4 was low. She responded well to danazol and had no further attacks of angioedema.

Adult↗

PubMed1995

Tissue humoral response to intact and ruptured silicone gel-filled prostheses.

Biopsies of the fibrous capsule in 31 women undergoing explanation of gel-filled breast prostheses and in 3 women with silicone gel-associated granulomas were tested for the presence of IgG, IgM, IgA, C3 complement, and fibrin using fluorescent antisera. Of a total of 41 prostheses removed, 9 were found to be ruptured but contained within the fibrous capsule or immediately adjacent to it. In the 3 women undergoing granuloma excision only, the sites were the arm (2) and the chest/axilla (1). In one patient, IgG, C3, and fibrin were detected in the capsule of an intact prosthesis. C3 and fibrin were present in the capsule surrounding one ruptured prosthesis. Fibrin was detected in the capsule of one other patient. Bilateral capsules surrounding intact prostheses removed from 4 patients with collage-vascular diseases were negative for C3, fibrin, and immunoglobulins, as were the 3 granulomas from distant sites. Hematoxylin and eosin stains revealed a typical foreign-body response to gel in almost all cases. Both T- and B-cell lymphocytes are present in the infiltrate surrounding silicone gel. In this study, chronic exposure to silicone gel-filled prostheses did not result in antibody deposition or complement activation in the fibrous capsule or in the tissue surrounding gel droplets.

Antibody Formation↗

PubMed1992

Factors influencing the interaction of herpes simplex virus glycoprotein C with the third component of complement.

The factors influencing the interaction of herpes simplex virus (HSV) glycoprotein C (gC) with the third component of complement (C3) were investigated in this study. The ability of gC of HSV type 1 (gC-1) to bind to the C3b fragment of C3 was found to be influenced by cell specific processing of gC-1 in a different manner, binding being remarkably enhanced in some cell lines following removal of sialic acid residues. Testing several intertypic recombinants of HSV we found that only strains expressing gC-1 exhibited binding to C3b, even though their genome consisted mainly of HSV-2 sequences in some recombinants. Expression of type-2 glycoproteins gB, gD, gE, gG, gH, and gI did not alter the ability of gC-1 to bind to C3b. Rosetting of HSV-1 infected Vero cells with C3b-coated red blood cells (EAC) was found to be temperature dependent and could be inhibited with purified C3b and anti-C3 antibodies. Polyanions like heparin or dextran sulfate were also inhibitory in a dose dependent manner, whereas C3d, neomycin and other aminoglycoside antibiotics failed to block. As the tested polyanions are also known to inhibit the infectivity of HSV, it could be speculated, that the complement binding function and the heparin-binding/attachment function of gC might be related.

Amino Acid Sequence↗

PubMed1975

Purification and partial characterization of human and porcine C3a anaphylatoxin.

C3a anaphylatoxin is a protein fragment generated enzymatically in serum during activation of the third component of complement (C3). A four-step procedure is described for the purification of human and porcine C3a anaphylatoxins from their respective sera after activation with inulin. Because serum carboxypeptidase rapidly inactivates C3a, the inhibitor epsilon-aminocaproic acid (EACA) was added during C3 activation, thus permitting isolation of fully active C3a anaphylatoxins directly from serum. A 2000-fold purification of C3a was achieved with an average 30% recovery assuming total conversion of C3 during treatment of serum with inulin. Human C3a anaphylatoxin obtained through the action of the C3 activating enzyme of the "alternate" pathway appeared nearly identical with the C3a obtained from isolated C3 after treatment with the C4,2 enzyme of the "classical" pathway or with trypsin. Comparisons were made between various properties of human and porcine C3a anaphylatoxins. The molecular weights differed only slightly. Electrophoresis on a cellulose acetate strip at pH 8.6 indicated a difference of approximately one net charge between human and porcine C3a, with the human anaphylatoxin exhibiting the more basic behavior. Although the amino acid compositions are similar, significant differences exist. The most marked difference was the total absence of threonine residues in porcine C3a. The NH2-terminal sequences of 20 amino acid residues were examined; homology existed for 16 of the 20 positions. Although partial analysis of the primary structure of human and porcine C3a indicates approximately 80% homology, no immunological cross-reactivity between the anaphylatoxins could be detected with antisera produced to either human or porcine C3a. In spite of the structural differences, the biological activities of porcine and human C3a were essentially identical. Smooth muscle contraction, increase in vascular permeability, and release of histamine from mast cells were similarly induced by equal amounts of anaphylatoxin from either human or porcine origin. Porcine C3a, like human C3a, was shown to contain a COOH-terminal arginyl residue essential for smooth muscle contraction and for induction of histamine release from mast cells. The sequence adjacent to the COOH-terminal arginine was Leu-Ala-Arg-COOH for both humans and porcine C3a. Current evidence suggests common mechanisms exist for the generation of C3a in various animal species and that the two known C3 activating enzymes in serum exhibit trypsin-like specificity.

Amino Acid Sequence↗

PubMed1990

Expression of HLA DR antigens, Fc IgG and C3 receptors on lung macrophages in sarcoidosis and idiopathic lung fibrosis.

The studies concerned an expression of HLA DR antigens, Fc IgG receptors and C3 complement on lung macrophages in patients with active sarcoidosis and idiopathic lung fibrosis as well as in the control group of smokers and nonsmokers. Macrophages were isolated by broncho-alveolar lavage with the aid of bronchofiberoscope. The expression of HLA DR antigens, Fc IgG and C3 receptors was tested before during and after the treatment. The percentage of macrophages with HLA DR antigens and Fc IgG receptors was observed to be high before the treatment in the examined as well as in the control groups. During steride treatment, the percentage of macrophages with HLA DR antigens and Fc IgG receptors diminished in relation to the control (p less than 0.05). After termination of the treatment, the percentage of macrophages with HLA DR antigens and Fc IgG receptors was lower than before the treatment. The differences in percentages of macrophages with C3 receptors did not achieve statistical significance in neither of the groups examined in the period of treatment.

Adult↗

PubMed2000

Clinical outcome and predictors of disease evolution in patients with incomplete lupus erythematosus.

To determine the outcome and identify risk factors for evolution into systemic lupus erythematosus (SLE) in a population of incomplete lupus erythematosus (ILE) patients, we studied the clinical and serologic manifestations in a cohort of 87 ILE patients. ILE patients had at least one but less than four of the American College of Rheumatology (ACR) classification criteria of SLE and did not present distinctive clinical features or meet classification criteria of other connective tissue diseases. The patients that remained with ILE were compared with patients that evolved into SLE and with a cohort of 94 SLE patients. The mean disease duration and follow up of ILE patients were 4.4 +/- 4.1 and 2.2 +/- 2.4 years respectively. Eight patients evolved into SLE, but none presented major organ damage. At baseline, patients that remained with ILE were less likely to have photosensitivity, elevated anti-dsDNA and decreased C3 complement than patients that evolved into SLE. At the end of the study, malar rash and oral ulcerations were also less frequent in the ILE group. Compared with all SLE cases, ILE patients were less likely to have photosensitivity, malar rash, oral ulcers, Raynaud's phenomenon, arthritis, low C3, low C4, positive anti-dsDNA, anti-Sm, anti-RNP, anti-Ro and anti-La antibodies at baseline. Hazard analyses showed that malar rash, oral ulcers, elevated anti-dsDNA and decreased C4 were associated with SLE occurrence. In conclusion, this study suggests that ILE represents a mild spectrum of lupus in which mucocutaneous and serological abnormalities are associated with progression into SLE.

Adult↗