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PubMed1969

C3 leukotactic factors produced by a tissue protease.

When various rat tissues are incubated in homologous serum, a factor chemotactic in vitro for neutrophils is generated. The amount of chemotactic activity is a function of duration of incubation and the quantity of heart tissue or serum employed. Addition of trypsin inhibitor or antibody to the third component of complement (C3) precludes generation of chemotactic activity. In addition, antibody to C3 ablates chemotactic activity even after its formation. Purified human C3 (beta(1C)-globulin) effectively substitutes for serum in the generation of chemotactic activity by heart tissue. The active product, as determined by gel filtration or by ultracentrifugal analysis in a sucrose density gradient, appears to be a cleavage product of C3 with a molecular weight of approximately 14,000. In addition, a larger C3 fragmentation product varying in molecular weight, depending upon experimental conditions, is also found. The protease in rat heart tissue capable of cleaving C3 into chemotactic fragments is a serine esterase with trypsin-like properties and can be inhibited by organophophorous compounds or trypsin inhibitors. The use of amino acid esters in the manner of competitive substrate inhibition confirms the trypsin-like nature of the protease. The presence of a protease in heart, and presumably in other normal tissues, capable of fragmenting C3 into factors with chemotactic activities may explain the development of the acute inflammatory response when tissues are non-specifically injured. If true, this would reinforce the role of the complement system in the mediation of nonimmunologically induced inflammation.

Amino Acids↗

PubMed1990

Elutable factors from latex-containing materials activate complement and inhibit cell proliferation. An in vitro biocompatibility study of medical devices.

Eluates from one all-silicone and two different combined silicone-latex catheters and one latex and one vinyl procedure glove were mixed with normal human serum and tested in a C3 complement activation assay. Simultaneously the eluates were tested in a cellular assay to measure inhibition of cellular proliferation. The combined silicone-latex catheters and the latex procedure glove caused a pronounced complement activation and inhibited cell proliferation. However, the response ranging was opposite in the two assays, suggesting that different soluble factors were responsible for the observed reactions. No complement activation or inhibition of cellular proliferation was observed for the all-silicone catheter and the vinyl procedure glove. Our results demonstrate that different assays should be taken into account when biocompatibility is evaluated.

Catheterization↗

PubMed2001

Immunological follow-up of hydatid cyst cases.

Hydatid disease is caused by Echinococcus granulosus. In this study, we aimed to investigate the benefit of monitoring cases with hydatid cyst by means of immune components in patients in a long-term follow-up after surgery. Eighty-four preoperative and postoperative serum samples from 14 cases undergoing surgery for hydatid disease were evaluated in terms of immune parameters, such as total and specific IgE, IgG, IgM, IgA and complement. Total and specific IgE were determined by ELISA. Specific IgG levels were measured by indirect hemagglutination. Total IgG, IgM, IgA and complement (C3 and C4) were detected by nephelometry. Imaging studies were also carried out during the follow-up. In none of the patients hydatid cysts were detected during the follow-up. Total IgE levels in the sera of the patients decreased to normal six months after surgery. Although specific IgE against echinococcal antigens decreased one year after operation, levels were still significantly high. There were no changes in the levels of anti-Echinococcus IgG and total IgG in follow-up period. Additionally, other parameters, such as IgA, IgM, C3 and C4, were not affected.

Adult↗

PubMed1984

Early cellular and biochemical alveolar responses following intra-tracheal inoculation with low dose of asbestos and quartz.

The study of broncho-alveolar lavage harvested from rats intratracheally dusted with chrysotile (0.5 mg), leached chrysotile (0.5 mg), crocidolite (0.5 mg) and quartz (0.5 and 5 mg) indicated: 1. A cytotoxic lysis of alveolar macrophages in relation to phagocytosis of dust particles in the following decreasing order: quartz, crocidolite, chrysotile. 2. Regarding cell intensity and duration while asbestos, even leached chrysotile, gave merely an early and transient response. This cell recruitment concerned mostly PMN leukocytes and at a less extent alveolar macrophage. 3. Cell recruitment was associated with an increased protein and phospholipids alveolar content. The increase of proteins came probably mostly from an inflammatory serum exudation. However, an increase synthesis of complement C3 and phospholipids is not excluded.

Animals↗

PubMed2005

A DeImmunized chimeric anti-C3b/iC3b monoclonal antibody enhances rituximab-mediated killing in NHL and CLL cells via complement activation.

Complement-dependent cytotoxicity (CDC) is a key mechanism of Rituximab (RTX) action in killing non-Hodgkin's lymphoma (NHL) cells both in vitro and probably in vivo. A DeImmunized, mouse/human chimeric monoclonal antibody (Mab), H17, specific for cell-associated complement C3 cleavage products, C3b and iC3b, was generated to enhance RTX-mediated killing of target cells by CDC. When NHL cell lines were treated with RTX and H17 in the presence of complement for 1 h, there was 40-70% more cell death than that observed with RTX alone. The enhancing effect of H17 was also seen over longer treatment periods. H17 was tested ex vivo against primary cells from NHL and chronic lymphocytic leukemia (CLL) patients. In RTX-resistant NHL samples, H17 enhanced RTX-mediated killing; in the remaining samples RTX + complement alone promoted more than 80% killing, and no significant enhancement was observed. The H17 antibody also increased RTX-mediated killing in four out of nine CLL samples. H17 may have therapeutic applications in NHL and CLL treatment as an adjunctive therapy to RTX. It might also enhance the activity of other therapeutic antibodies that work through CDC.

Animals↗

PubMed1997

The association of the subunits of component C3 of hagfish complement is unstable and leads to novel degradation during electrophoresis.

An opsonic molecule that is designated the third component of hagfish complement (HC3), and a fragment of HC3 known as HC3b have recently been identified in the hagfish, Eptatretus burgeri. These proteins were purified from plasma and generated a set of several bands and/or smears during SDS-PAGE under standard, non-reducing conditions. Two-dimensional electrophoretic analysis of the proteins under non-reducing and reducing conditions revealed the breakdown of polypeptides at the site of a thioester bond and the concomitant partial release of a split product, depending on the weak covalent or non-covalent association of polypeptide chains, in a large fraction of molecules of HC3 during SDS-PAGE. Moreover, the heterogeneity of HC3b can be ascribed to the different configurations of subunits. A similar phenomenon was not observed in the case of lamprey C3, even though breakdown of polypeptides at a thioester bond did occur in some molecules.

Animals↗

PubMed1988

Lipid tolerance in children receiving long-term parenteral nutrition: a biochemical and immunologic study.

The effect of intravenously administered lipids (intralipid) on immunologic function, complement, and coagulation was prospectively studied over 1 year in 15 children. The mean age of the children was 52.4 +/- 37.9 months; they had received total parenteral nutrition for an average of 3 years. Immunoglobulins (IgA, IgM, IgG), coagulation studies (platelets, prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, fibrinogen degradation products, factor V) and components of complement (C3, C4, and CH100) were analyzed. Activation of monocytes by opsonized zymosan was measured by chemiluminescence and compared with that of normal control subjects. The clinically stable children had normal monocyte activation and normal complement levels. The PT and PTT values were significantly increased but improved with increased intralipid dose; other coagulation factors were normal. Acutely sick children, however, had decreased fat tolerance with significantly increased serum triglyceride levels and PT and PTT values; their monocyte activation and complement factors remained normal. These data indicate that the dose of intralipid should be lowered during acute illnesses; we suggest close monitoring of PT and PTT values and of serum triglyceride and cholesterol levels to avoid the fat overload syndrome.

Blood Chemical Analysis↗

PubMedDate not supplied

Immunological profile of patients with non-cirrhotic portal fibrosis.

The aetiopathogenesis of non-cirrhotic portal fibrosis (NCPF), a common cause of portal hypertension in India, is not known. To study the immune status of NCPF patients and to see whether immunological mechanisms have a role to play, humoral and cell-mediated immunological studies were carried out in 43 patients with NCPF and compared with equal number of matched healthy controls and 31 patients with compensated liver cirrhosis. Serum immunoglobulin A (IgA) and complement (C3, C4) levels were significantly (P less than 0.001) lower in NCPF patients compared with controls and cirrhotics. There was no significant difference between the total or the relative concentration of the immunoglobulins and complements between NCPF patients and healthy controls, but, in patients with cirrhosis, concentration of all the immunoglobulins was higher. The cutaneous response to dinitrochlorobenzene was poorer in patients with NCPF, but the difference between cirrhotics and controls was not significant. A decrease in the suppressor/cytotoxic (T8) phenotype of lymphocytes in the peripheral blood and an increase in the ratio of helper/inducer (T4) and T8 lymphocytes was seen in patients with NCPF and cirrhosis. Although these results indicate definite immunological abnormalities in NCPF patients, their role in the pathogenesis of NCPF remains to be investigated.

Adult↗

PubMed2001

Application of a direct flow cytometric erythrocyte immunofluorescence assay in dogs with immune-mediated hemolytic anemia and comparison to the direct antiglobulin test.

A direct flow cytometric erythrocyte immunofluorescence assay (FC) was developed and compared with the direct antiglobulin test (DAT) for detection of erythrocyte-bound immunoglobulin (IgG and IgM) and complement (C3) in dogs with immune-mediated hemolytic anemia (IMHA). Tests were performed on erythrocytes from 13 healthy nonanemic dogs and from 13 anemic dogs with IMHA. The FC and DAT were negative for erythrocyte-bound immunoglobulin in all healthy dogs. The FC was negative for erythrocyte-bound C3 in 12 healthy dogs and positive in 1 healthy dog, and the DAT was negative for C3 in all healthy dogs. Of the 13 IMHA dogs tested for erythrocyte-bound IgG, 12 were positive using the FC and 7 were positive using the DAT. Sensitivity for the detection of erythrocyte-bound IgG in the 26 dogs was 92% for FC and 53% for DAT. Specificity for detection of erythrocyte bound IgG for FC and DAT was 100%. The addition of IgM and/ or C3 did not increase the sensitivity for FC or DAT. In this group of dogs, the FC provided a more rapid, cost-effective, sensitive, objective method to quantitate erythrocyte-bound immunoglobulin and/or complement compared with the currently used DAT.

Anemia, Hemolytic↗

PubMed1978

Detection of circulating immune complexes in patients with glomerulonephritis.

143 patients were evaluated clinically on the basis of the renal biopsy. Three methods for detecting circulating immune complexes (CIC) were employed: complement consumption test, inhibition of erythrocyte antibody IgG-EA rosette forming test and optical density of 4% PEG precipitated sera. CIC were present in the sera of all patients with acute poststreptococcal glomerulonephritis (2 weeks after streptococcal infection of the throat). In a group of patients with chronic glomerulonephritis the highest values in positive results were observed in lupus nephritis, chronic proliferative glomerulonephritis and chronic submicroscopic glomerulonephritis. These results were compared with levels of total hemolytic complement, C3, C4 components and serum immunoglobulins (IgA, IgG, IgM).

Antigen-Antibody Complex↗

PubMed1999

Humoral response to herpes simplex virus is complement-dependent.

The complement system represents a cascade of serum proteins, which provide a major effector function in innate immunity. Recent studies have revealed that complement links innate and adaptive immunity via complement receptors CD21/CD35 in that it enhances the B cell memory response to noninfectious protein antigens introduced i.v. To examine the importance of complement for immune responses to virus infection in a peripheral tissue, we compared the B cell memory response of mice deficient in complement C3, C4, or CD21/CD35 with wild-type controls. We found that the deficient mice failed to generate a normal memory response, which is characterized by a reduction in IgG antibody and germinal centers. Thus, complement is important not only in the effector function of innate immunity but also in the stimulation of memory B cell responses to viral-infected cell antigens in both blood and peripheral tissues.

Animals↗

PubMed1971

Complement-derived leukotactic factors in inflammatory synovial fluids of humans.

A large per cent of rheumatoid synovial fluids contain chemotactic activity for rabbit granulocytes (neutrophilic). The chemotactic activity is, in large part, related to the fifth (C5) and sixth (C6) components of human complement; a combination of physical-chemical techniques indicates the activity to be attributable to C567 and C5a, a cleavage product of C5. Many rheumatoid synovial fluids contain a C5-cleaving enzyme which, on the basis of substrate specificity and susceptibility to inhibitors, is very similar to an enzyme extractable from lysosomal granules of human and rabbit granulocytes. Inflammatory nonrheumatoid synovial fluids contain chemotactic activity that is related to cleavage products (C3a) of the third component of human complement (C3). Also found in these fluids is a C3-cleaving enzyme capable of producing C3a. Of the other synovial fluids examined, lupus fluids were remarkable by their total lack of chemotactic activity. These findings record for the first time the presence of complement-derived chemotactic factors in pathological human fluids.

Antigen-Antibody Reactions↗

PubMedDate not supplied

Persistent histological and immunological abnormalities in congenital syphilitic glomerulonephritis after disappearance of proteinuria.

A 40-day-old male infant suffered from generalized anasarca, proteinuria and hematuria. Serologic study revealed marked elevation of antibody titer against Treponema pallidum, the same serologic finding was also noted in both his parents. Two weeks of treatment with penicillin was given. The edema subsided 7 days later, and proteinuria and hematuria disappeared 20 days after the initiation of penicillin treatment. At the age of 60 days, all the clinical symptoms and signs vanished; urinalysis and renal function were all within normal limits and renal biopsy was performed. Pathologic study revealed membranous glomerulonephritis with deposition of IgG, IgM and complement C3, C1q, C4 and treponema antigen in the subepithelial area of the glomerular basement membrane. These phenomena suggest that treponemal antigen-antibody complexes were deposited in the glomeruli and activated the classic pathway of complements, leading to an immune complex nephritis. Immunologic study revealed that the patient had high circulating helper T cells (CD4 cells), low level of suppressor T cells (Leu2+15+ cells) with high CD4/CD8 ratio. It was accompanied by detectable circulating immune complex and high titer of T. pallidum hemagglutinin antibody titer. This change suggests that abnormal immune regulation may play an important role in the development of syphilitic glomerulonephritis.

Glomerulonephritis↗

PubMed1975

Glomerular involvement in human kala-azar. A light, immunofluorescent, and electron microscopic study based on kidney biopsies.

Glomerular involvement characterized by mesangial cell proliferation with fibrillar thickening of the axial region and deposits of immune complexes is reported in three human cases of kala-azar. IgG was seen in all 3 and Igm in 2 patients. Complement (C3) was detected in the glomeruli in all cases and fibrinogen in the only case in which it was tested for. The deposits appeared mainly along the mesangium and their staining was particularly strong for complement and IgG. Electron microscopy detected granular electron dense deposits mainly close to mesangial cells. In one case clumps made us of electron dense lamellae were seen in the glomerular basal membrane interpreted as evidence of focal membranolysis. No granulocytes were seen in the glomeruli. Attempts to demonstrate antigen were unsuccessful. The pattern of the lesion resembles that described in the kidney of human cases of hepatosplenic schistosomiasis, and the distribution of the deposits suggests that relatively large, poorly soluble complexes formed either in the presence of excess antigen or, under certain circumstances, in the presence of excess antibody, are trapped in the glomerular capillaries. The aggregates are partially shunted to the mesangial cells, which enlarge and proliferate.

Adult↗

PubMed2001

Cell-specific regulation of the CD21 gene.

The Complement Receptor Type 2 (Cr2-145,CR2, CD21) is an important receptor in the innate and acquired immune response. CD21 is produced by B cells and follicular dendritic cells, where it binds cleavage products of the C3 complement protein. CD21 facilitates internalization of immune complexes by B cells to enhance antigen presentation. CD21, in association with CD19/CD81, also serves as a coaccessory activation complex with the B-cell antigen receptor, permitting a lower antigen concentration to achieve maximal B-cell activation. CD21 traps immune complexes on the surface of follicular dendritic cells and displays them to activated B cells in germinal centers. Much work has been conducted to determine the transcriptional control mechanisms dictating CD21 expression. Appropriate transcriptional control of the CD21 gene evidently requires the CD21 promoter, as well as intronic sequences with enhancer and suppressor functions. Chromatin structure has been implicated in regulating the coordination of CD21 promoter and intronic control sequences by regulating access to them by putative transcription factors. This review assesses the past and current research into CD21 transcriptional regulation and offers insight into future experimental directions.

Animals↗

PubMed1986

Enhancement of phagocytosis by a calmodulin antagonist (W-7) in mice.

W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide], a well-known inhibitor of the calmodulin-dependent processes, strongly enhanced phagocytosis and ingestion of polystyrene latex beads into the peritoneal macrophages of BALB/c mice after the i.p. injection, whereas W-5 [N-(6-aminohexyl)-naphthalene sulfonamide], a less effective calmodulin antagonist, was much weaker than W-7. Binding of the third component of complement (C3) cleavage to the C3 receptor on macrophages after the i.p. injection of W-7 was enhanced as shown by the fluorescent antibody technique. These data suggest that calmodulin plays an important role in the phagocytosis of macrophages through the complement system.

Animals↗

PubMed1980

Chronic relapsing experimental allergic encephalomyelitis. Immunohistochemical studies.

The immunohistochemical staining of immunoglobulins (Ig), complement (C3), and fibrinogen in chronic relapsing experimental allergic encephalomyelitis lesions showed different staining patterns in the acute vs the chronic stage of the disease. In the acute stage, Ig, C3, and fibrinogen were present in the perivascular tissue of the brain and the spinal cord. In hyperacute-type lesions, the binding of Ig and C3 to the parenchyma was especially pronounced. The chronic stage of the disease was characterized by Ig-containing cells and Ig binding to white matter in actively demyelinating lesions. Linear or granular deposits of immunoglobulin and complement, reminiscent of those described in immune complex disease, were found in the choroid plexus.

Animals↗

PubMed2001

Short term effect of atorvastatin and vitamin E on serum levels of C3, a sensitive marker of the risk of myocardial infarction in men.

C3 complement is produced in response to macrophage activation and is a reliable marker of the risk of myocardial infarction in men. This study was designed to ascertain whether the treatment with atorvastatin, a powerful cholesterol lowering drug, and/or vitamin E, a natural antioxidant, may induce a short term decrease in serum C3 in subjects with persistently elevated levels. From an initial random sample of 1100 men aged 55-64 years, 140 subjects with 3 consecutive C3 measurements in the high tertile (>1.19 g/l) were selected. Those with total cholesterol <5.56 mmol/l were double blindly randomized in groups 1 (placebo, N = 28, G1) and 2 (vitamin E 600 IU/day, N= 30, G2). The subjects with total cholesterol values >5.56 mmol/l were randomized in groups 3 (placebo, N= 30, G3), 4 (atorvastatin 10 mg/day, N = 27, G4) and 5 (atorvastatin 10 mg/day + vitamin E 600 IU/day, N = 25, G5). After 3 months C3 levels were substantially unchanged in the first 4 groups, while in G5 a very significant decrement occurred: -0.070 g/l (5.2%); 95% CI 0.043-0.098; p <0.0001. "Normal" levels of C3 (< 1.19 g/l) were reached by 28% of G5 subjects. In G2 and G5 vitamin E levels increased by 60 and 36%, while in G4 they decreased by 23% (p < 0.0001), paralleling cholesterol and triglyceride fall. In all groups a progressive decrease in HDL cholesterol occurred (-17%, p < 0.0001). In conclusion, treatment with atorvastatin plus vitamin E for three months can lower persistently elevated C3 levels.

Anticholesteremic Agents↗