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Results for “Complement C3”

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PubMed1988

A simple isolation procedure for functionally pure components of the bovine alternative complement pathway (ACP) C3 convertase and bovine conglutinin (K).

A simple multicomponent isolation procedure for bovine C3, factor B, factor D and conglutinin (K) from a single serum sample is described. The components of the alternative pathway C3 convertase were isolated in milligram quantities from 800 ml bovine serum and were found to be functionally pure with respect to each other and to factors H and I.

Animals↗

PubMed1981

Isolation of a biologically active macrophage receptor for the third component of complement.

C3b, the major cleavage fragment of the third component of complement (C3), has been demonstrated to bind to a specific receptor on various mammalian cells. Tissue-bound C3b receptors have also been demonstrated, most conclusively in renal glomeruli. On interaction with C3b, C3b receptors are thought to initiate cellular functions such as phagocytosis and to determine the fate of complement-fixing soluble and particulate immune complexes. We report here the isolation by affinity chromatography of a macrophage glycoprotein with an apparent molecular weight (MW) of approximately 64,000 that has properties expected of the C3b receptor. It is a cell-surface macromolecule (labelled with 125I and lactoperoxidase) which, in its isolated state, retains the ability to bind both C3 and C3b.

Animals↗

PubMed1992

Immunohistochemical analysis of otic capsule osteogenesis in the Palmerston North autoimmune mouse.

Autoimmunity and the immune complex disease associated with it have been hypothesized to be the cause of several idiopathic diseases of the inner ear--including the new bone formation associated with otic capsule osteogenesis and otosclerosis. The Palmerston North (PN) autoimmune mouse strain, which exhibits both spontaneous systemic autoimmune disease and otic capsule bone formation, has been proposed as a model relating these two disease processes. To investigate the potential role of immunopathologic processes in PN otic capsule lesion formation, inner ears from PN mice were immunostained for the presence of IgG and complement (C3), two immunologic markers involved in the development of the vascular and perivascular changes associated with immune complex deposition. Both systemic autoimmune disease and otic capsule bony lesions were confirmed in all animals. However, immunohistochemical analyses did not establish a direct relationship between the two conditions as complement was absent in all lesions and IgG stained positive in only one instance. These results suggest that immune complex deposition is not directly involved in the otic capsule lesions of the PN mouse, and alternate mechanisms relating autoimmune disease and otic capsule osteogenesis must be explored.

Animals↗

PubMed2002

[Distribution of the ABO blood groups and the HP, TF, GC, PI and C3 serum proteins in Yakuts].

In Yakut populations examined, polymorphisms of immunological and serum protein markers, including AB0 and Rhesus blood groups, HP, TF, GC, PI and C3, were revealed. Gene frequencies for the systems studied fell into the following ranges: AB0 system: r, 0.514 to 0.663; p, 0.136 to 0.306; q, 0.110 to 0.337; haptoglobin HP*1: 0.214 to 0.431; transferrin TF*C: 0.700 to 1.0; group specific component GC*1: 0.821 to 0.978; PI*M1 proteinase inhibitor (or alpha 1-antitrypsin) PIM1: 0.860 to 0.946; and third component of the complement C3*F: 0.031 to 0.143.

ABO Blood-Group System↗

PubMed1993

The biological roles of the third component of complement in osteoclast formation.

We previously reported that 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3] tissue-specifically stimulated the production of the third component of complement (C3) in bone in vitro and in vivo. In the present study, we examined the possible roles of C3 in bone using bone marrow cultures with antibodies against C3 and C3 receptors (Mac 1, 8C12, and 7G6) and the purified mouse C3 protein. The C3 protein produced preferentially by stromal cells in response to 1 alpha,25-(OH)2D3 was distributed in macrophage-like mononuclear cells and small cells with few nuclei. Adding anti-C3 antibody together with 1 alpha,25-(OH)2D3 to bone marrow cultures greatly inhibited not only the appearance of tartrate-resistant acid phosphatase (TRAP)-positive mononuclear and multinucleated cells, but also the growth of macrophage-like mononuclear cells and stromal cells. The inhibitory effect of anti-C3 antibody on osteoclast-like cell formation was most prominent when it was added between days 2-4 of the 6-day culture period, which corresponded to the late proliferative phase and the early differentiation phase of osteoclast development. Adding anti-C3 receptor antibodies also inhibited osteoclast-like cell formation induced by 1 alpha,25-(OH)2D3. When C3 receptors were detected by the binding of C3-coated sheep red blood cells or immunostaining, the localization of C3 receptor-positive cells coincided exactly with that of C3 protein-positive cells. C3 receptors were expressed mainly in macrophage-like mononuclear cells, TRAP-positive mononuclear cells, and TRAP-positive small cells with few nuclei. TRAP-positive large cells with many nuclei were totally negative for C3 receptors. When macrophage-colony-stimulating factor (M-CSF), the purified C3 protein, and 1 alpha,25-(OH)2D3 were added to bone marrow methylcellulose cultures, separately or in combination, M-CSF-dependent colony formation was strikingly inhibited by 1 alpha,25-(OH)2D3, but the inhibition was prevented by simultaneously adding C3. These results provide additional evidence that osteoclast progenitors are indeed cells of the monocyte-macrophage lineage. It is likely that the C3 produced by stromal cells in response to 1 alpha,25-(OH)2D3 is somehow involved in osteoclast development by potentiating M-CSF-dependent proliferation of bone marrow cells and induction of osteoclast differentiation.

Acid Phosphatase↗

PubMed1980

An improved three-step method for the purification of the third component of human complement.

This paper describes a three-step purification method for the third component of human complement (C3) from plasma. The method consists of PEG precipitation, DEAE-cellulose chromatography and preparative isofocusing in a granulated dextran gel, with pH range 5--8. From this last step, a highly purified form of native C3 was obtained as indicated by immunoelectrophoresis and polyacrylamide gel electrophoresis analysis. The average final recovery was 20%.

Binding Sites↗

PubMed2006

New progesterone receptor antagonists: phosphorus-containing 11beta-aryl-substituted steroids.

A new series of phosphorus-containing 11beta-aryl-substituted steroids have been synthesized in an eight-step sequence involving a palladium-catalyzed coupling reaction to introduce a phosphorus group onto the aromatic ring. The compounds were evaluated for progesterone receptor (PR) antagonist activity in a T47D cell-based assay and for glucocorticoid receptor (GR) antagonist activity in an A549 cell-based assay. The structure-activity relationships of these compounds are discussed. Selected compounds were tested in vivo in a rat complement C3 assay.

Alkaline Phosphatase↗

PubMed2002

Polystyrene derivatives as candidates for extracorporeal adsorption of Factor VIII antibodies in the management of haemophiliac patients.

BACKGROUND AND OBJECTIVES: This article presents a new approach for removing the Factor VIII inhibitors (anti-FVIII) in haemophiliac patients by immunoadsorption using an affinity matrix. MATERIALS AND METHODS: Ten blood samples from haemophiliac patients with anti-FVIII were assayed for antibodies, total immunoglobulins, procoagulant proteins and complement C3 protein after circulation over one or two columns filled with the polymers under investigation. RESULTS: These new synthetic sorbents are able to remove in vitro 90% of anti-FVIII from haemophiliac plasma with inhibitors (up to 540 Bethesda Units/ml). Neither coagulation factor adsorption nor effects on complement system activation were observed. CONCLUSIONS: The data presented clearly show that these polymers allow a rapid and efficient reduction of inhibitor titre. In view of the parameters studied, these polymers fulfil the requirements for use in a blood purification process to decrease high inhibitor titres without losing essential proteins.

Autoantibodies↗

PubMed1990

Acute phase proteins in neonatal rabbits: diminished C-reactive protein response.

Acute phase protein response accompanies tissue injury, inflammation, or infection. During the acute phase, serum levels of C-reactive protein (CRP) can increase as much as 1,000-fold. We found that in response to an intramuscular injection of turpentine, neonatal rabbit CRP-specific RNA and serum CRP rose minimally. In contrast, adult serum levels of CRP increased 20-fold and mRNA for CRP in adults increased commensurately. However, during neonatal acute phase reactions, changes in the synthesis of the third component of complement (C3) and albumin were induced, implying a dysynchronous development of the response of various acute phase proteins.

Acute-Phase Reaction↗

PubMed1978

Glomerulonephritis in dermatitis herpetiformis. A case study.

A patient with dermatitis herpetiformis, proteinuria and reduced renal function is described. A renal biopsy studied by light and immunofluorescence microscopy revealed a glomerulonephritis with deposits of predominantly IgA and complement C3. Deposits of IgA and C3 were also demonstrated in a biopsy from normal skin, and a common pathway for the skin and renal lesions is suggested.

Complement C3↗

PubMed1977

Combined T and B lymphocyte marker test in lymphoproliferative disorders.

The combined T and B lymphocyte marker test of Mendes et al (1974) has been developed to provide an easy, reproducible test for clinical practice. It has been used to study subpopulations of peripheral lymphocytes in patients with lymphoid malignancies. Significant increases in the numbers of lymphocytes which bind both sheep erythrocytes (E) and the fixed, third component of complement (C3) have been found using this test, in the peripheral blood of all untreated lymphosarcoma (L/SA) patients and T cell acute lymphoblastic leukaemia (ALL) patients. Such increases were not found in blood from patients with chronic lymphatic leukaemia (CLL), other non-lymphoid malignancies, null-cell ALL or normal individuals. These mixed E and C3 receptor bearing cells may be Fc receptor positive and represent a separate subpopulation of lymphocytes.

B-Lymphocytes↗

PubMed1988

Post-translational processing of the murine third component of complement.

The biosynthesis and secretion of the third component of complement (C3) has been studied with the macrophage cell line J774.2. C3 is initially synthesized as a single polypeptide chain precursor termed pro-C3, of relative molecular weight (Mr) 170,000 that is post-translationally modified by proteolytic cleavage into two polypeptides linked by disulphide bonds. The larger polypeptide, termed the alpha chain, has an Mr of 110,000-115,000, while the smaller beta chain has an Mr of 55,000-60,000. Pulse-chase experiments indicate that the proteolytic processing of pro-C3 occurs intracellularly, just prior to secretion. Unlike human C3, which has carbohydrate on both the alpha and beta chains, only the alpha chain of murine C3 is glycosylated. The carboxylic ionophores monensin and nigericin totally inhibit the proteolytic processing of pro-C3 at a concentration of approximately 10(-6) M. This block on proteolytic processing was shown not to be mediated by changes in intracellular pH induced by the disruption of proton gradients. Rather, data from experiments using carboxylic ionophores and other perturbants of cellular physiology indicated that the enzyme(s) responsible for the proteolytic cleavage of pro-C3 either reside in a cellular compartment with a neutral pH or are proteinases active over a relatively broad pH range.

Ammonium Chloride↗

PubMed1984

A method for isolation, characterization, and quantitation of soluble proteins in uterine cervical secretion.

By sodium chloride (0.66 M) extraction of cervical mucus on an inert chromatographic bed, soluble proteins can be conveniently recovered. Individual proteins such as albumin and IgG may then be quantitated by immunonephelometry. The procedure has been shown to improve reproducibility which is very poor in the presence of mucin. By concentrating the NaCl extract by centrifiltration, proteins present in low concentrations - such as complement C3 - can be measured. The concentrate has also been used for analyses by isoelectric focusing or gradient gel electrophoresis on polyacrylamide gels.

Adult↗

PubMed1977

Humoral components of immunological response in nephrotic syndrome.

Serum and urine were collected from 58 patients with nephrotic syndrome. Immunoglobulins (IgA, IgG and IgM), complement (C3) and transferrin levels were measured by single radial immunodiffusion. The extent of glomerular injury was estimated by determining the selectivity of proteinuria. The relationship between the severity of glomerular damage and serum concentrations of immunoglobulins and complement was assessed. Higher IgM and lower IgG serum concentrations were found in nephrotic patients than in normal controls (157 +/- 108 mg+ vs 127 +/- 38 mg% for IgM, 929 +/- 537 mg% for IgG). The difference was statistically significant (p less than 0.05 for IgM, p less than 0.001 for IgG). No correlation was present between the selectivity of proteinuria and serum levels of IgA, IgM, IgG or C3. The results indicate that abnormalities in humoral components of the immune system are present in nephrotic patients and are probably related to a basic immunological defect in the patients rather than to the severity of glomerular damage.

Complement C3↗

PubMed1980

Evidence for presence of an internal thiolester bond in third component of human complement.

Treatment of the third component of human complement (C3) with methylamine results in a loss of hemolytic function and the appearance of a thiol group. Studies with [14C]methylamine have indicatd a stoichiometric and covalent reaction with the native protein. Hydrazine-inactivated C3 and C3b prepared with bovine trypsin were unreactive with [14C]-methylamine. Alkylation experiments with [1-14C]iodoacetamide have further established a 1:1 correspondence between methylamine incorporation and expression of the reactive thiol. Autoradiographic analyses of [14C]methylamine-treated C3 and methylamine-inactivated [1-14C]carboxyamidomethylated C3 after NaDodSO4/polyacrylamide gel electrophoresis have shown a specific incorporation of each radiolabel into the alpha polypeptide chain. [14C]Methylamine-treated C3 was immobilized on Sepharose 4B by reaction of the protein thiol with a mixed disulfide. Digestion with bovine trypsin in 4 M urea released 96% of the bound absorbance (at 280 nm) units; the radiolabel remained associated with the Sepharose beads. Peptide material labeled with 14C was eluted with dithiothreitol, carboxymethylated with [3H]iodoacetic acid, and chromatographed on Sephadex G-75. On Edman degradation S-[3H]carboxymethylcysteine was released at step 9 and gamma-glutamyl[14C]-methylamide was released at step 12. We interpret these data to indicate the presence of an internal thiolester bond in native C3. In addition, evidence is presented for an identical reactive site in alpha 2-macroglobulin.

Amino Acids↗

PubMed1976

Identification and quantitation of hypersensitivity reactions to intravenous anaesthetic agents.

It is not possible to distinguish between direct pharmacological effects and immune-mediated hypersensitivity reactions by clinical observation alone and errors may occur in the absence of laboratory tests. A convenient and simple test is the measurement of plasma complement C3 consumption and conversion in sequential blood samples taken at intervals over the 24 h following an adverse response.

Alfaxalone Alfadolone Mixture↗

PubMed2003

Role of complement-binding CD21/CD19/CD81 in enhancing human B cell protection from Fas-mediated apoptosis.

Defective expression of Fas leads to B cell autoimmunity, indicating the importance of this apoptotic pathway in eliminating autoreactive B cells. However, B cells with anti-self specificities occasionally escape such regulation in individuals with intact Fas, suggesting ways of precluding this apoptosis. Here, we examine whether coligation of the B cell Ag receptor (BCR) with the complement (C3)-binding CD21/CD19/CD81 costimulatory complex can enhance the escape of human B cells from Fas-induced death. This was warranted given that BCR-initiated signals induce resistance to Fas apoptosis, some (albeit not all) BCR-triggered events are amplified by coligation of BCR and the co-stimulatory complex, and several self Ags targeted in autoimmune diseases effectively activate complement. Using a set of affinity-diverse surrogate Ags (receptor-specific mAb:dextran conjugates) with varying capacity to engage CD21, it was established that BCR:CD21 coligation lowers the BCR engagement necessary for inducing protection from Fas apoptosis. Enhanced protection was associated with altered expression of several molecules known to regulate Fas apoptosis, suggesting a unique molecular model for how BCR:CD21 coligation augments protection. BCR:CD21 coligation impairs the generation of active fragments of caspase-8 via dampened expression of membrane Fas and augmented expression of FLIP(L). This, in turn, diminishes the generation of cells that would be directly triggered to apoptosis via caspase-8 cleavage of caspase 3 (type I cells). Any attempt to use the mitochondrial apoptotic protease-activating factor 1 (Apaf-1)-dependent pathway for apoptosis (as type II cells) is further blocked because BCR:CD21 coligation promotes up-regulation of the mitochondrial antiapoptotic molecule, Bcl-2.

Adaptor Proteins, Signal Transducing↗

PubMed1980

Hemolytic complement and serum C3 levels in Zebu cattle infected with Trypanosoma congolense and Trypanosoma vivax and the effect of trypanocidal treatment.

Total hemolytic complement and C3 levels were found to drop to 6.25% and 50% of preinfection levels, respectively, during trypanosome infections. Chemotherapeutic elimination of the trypanosomes with Berenil led to recovery of preinfection levels within 7 days and 11 days when cattle infected with Trypanosome congolense and Trypanosoma vivax, respectively, were treated 37 days after onset of infection. Recovery was slower in T. vivax-infected cattle treated on day 50. Berenil treatment had no effect on complement levels in control animals. The possible causes and implications of these low complement levels in bovine trypanosomiasis are discussed.

Amidines↗