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Results for “Complement Hemolytic Activity Assay”

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PubMed1999

Complement haemolytic activity (classical and alternative pathways), C3, C4 and factor B titres in healthy children.

Values of complement lytic activity of classical and alternative pathways, assessed by measuring the time required to lyse 50% of target red blood cells, and the concentration of complement components C3, C4 and factor B were estimated in the sera of 103 healthy children aged 3 to 14 y. Age-dependent variations were seen in the C3 and factor B concentrations, but not in C4, with the highest values found among 5-6-y-old children. Variations in classical and alternative lytic activity were not detected in this group of children, although the values are significantly different from our previously published data on adults, using the same kinetic assay (1). We also evaluated the relationship between the lytic activity of the classical (CPT) and alternative pathways (APT) and the levels of complement components. There were significant correlations between: APT and factor B, APT and C3, C3 and C4, C3 and factor B, and C4 and factor B concentrations. The normal ranges measured here can be used in the initial screening of Brazilian children presenting diseases involving the complement system. This study also contributes to a better understanding of the complement system ontogeny.

Adolescent↗

PubMedDate not supplied

Enzyme-linked immunosorbent assay (ELISA) for measles antibody. A comparison with haemagglutination inhibition, immunofluorescence and plaque neutralization tests.

An enzyme-linked immunosorbent assay (ELISA) for measles antibodies was compared with Plaque Neutralization (PRN), Haemagglutination inhibition (HI) and Fluorescent antibody (IFA) tests in 181 sera from vaccinated children and umbilical cord. Of 179 positive samples by the sensitive PRN, only two, with titers of 8, were negative by ELISA (copositivity of 98.9%). IFA and HI presented, respectively, copositivities of 93.3% and 82.7%. The ELISA presented a high sensitivity as well as a good reproducibility and represents an alternative for the time consuming PRN for detection of low measles antibodies.

Antibodies, Viral↗

PubMed2000

Complement activation by Proteus mirabilis negatively charged lipopolysaccharides.

Proteus mirabilis strains are human pathogens responsible for urinary tract infections and bacteremias and may be involved in rheumatoid arthritis. Lipopolysaccharide (LPS, bacterial endotoxin), the major component of the cell wall, is one of the virulence factors of Proteus. In the presented studies, we have investigated complement activation by LPSs isolated from P. mirabilis O10, O23, O30, and O43 strains, which differ in the number of negative COO- groups on their polysaccharide components. Four P. mirabilis strains studied were sensitive to complement-mediated killing, despite complement binding by their LPSs. The optimal complement binding by LPSs was detected in serum with functional assays for both the classical and alternative pathways. Complement activation in 80% serum by the smooth, uronic acid, and hexosamine containing P. mirabilis LPSs was not critically determined by the structure of their O-chain polysaccharides. One of four LPSs used as a model, P. mirabilis O10 LPS, fragmented C3 in an LPS dose- and time-dependent manner. It was detected by crossed-immunoelectrophoresis and capture ELISA with anti-C3c antibodies. The lower complement activation by 023 LPS correlates with its reduced C3 fragmentation, compared with three other Proteus LPSs studied. Rabbit anti-O antibodies enhanced the complement binding and factor C3 fragmentation by O10, O23, O30, and O43 P. mirabilis LPSs.

Animals↗

PubMedDate not supplied

[Ultramicro-ELISA for the detection of IgM antibodies anti M. leprae].

The availability of an ultramicroanalytic system (SUMA) and species-specific antigen of M. leprae obtained by chemical synthesis, have made possible the standardization and validation of an ultramicroELISA assay for detecting specific human IgM antibodies to this mycobacterium. The specificity of this test to demonstrate the infection with M. leprae was corroborated through a screening of 433 blood bank serum samples and other 265 from different groups (100, control group, 50 tuberculosis patients, 65 leprosy patients, 50 from household). The results obtained in the additional study of 140 household sero showed a high correlation (r = 0.98) with the conventional microELISA method. The use of SUMA allows saving reagents and time since sample handling, plate reading, print out and storing the data are computer assisted.

Antibodies, Anti-Idiotypic↗

PubMed1989

High-incidence of C9 deficiency throughout Japan: there are no significant differences in incidence among eight areas of Japan.

From 92,686 sera sent from hospitals throughout Japan to the Special Reference Laboratories for CH50 assay, we were able to classify 80 patients as C9-deficient using a sensitive screening test, as well as hemolytic and immunochemical C9 assays. The incidence of C9 deficiency was determined to be 0.086%, and there were no distinct differences among the eight areas of Japan tested. Serum CH50 levels of these C9-deficient patients varied widely (9.4-63.8 U/ml), and exhibited a higher value (average: 34.1 U/ml) than that of healthy C9-deficient individuals, probably due to elevated C3, C4, and C5 levels. These patients suffered from a variety of autoimmune, renal, and infectious diseases, which, however, are thought to be only incidentally associated with C9 deficiency.

Complement C9↗

PubMed1996

Attenuation of cardiopulmonary bypass-derived inflammatory reactions reduces myocardial reperfusion injury in cardiac operations.

In cardiac operations endopeptidase (protease) inhibitor may be beneficial in reducing myocardial injury when administered in the cardiopulmonary bypass prime. Nafamostat mesilate was evaluated in 20 patients who underwent coronary artery bypass grafting. The patients were divided into a control group (n = 10) and a nafamostat group (n = 10). Nafamostat (2 mg/kg per hour) was continuously given during cardiopulmonary bypass in the nafamostat group. The age, number of grafts, cardiopulmonary bypass time, and aortic crossclamp time were similar between groups. In the control group, neither tumor necrosis factor-alpha nor interleukin-1 levels showed any significant change during cardiopulmonary bypass, whereas interleukin-6 and interleukin-8 levels, percent expression of adhesion molecule (CD18) on neutrophils, and CH50 assay results increased significantly during cardiopulmonary bypass. As compared with the control group, the nafamostat group showed significantly lower levels of interleukin-6 (123 +/- 57 versus 40 +/- 22 pg/ml, respectively) and interleukin-8 (96 +/- 13 versus 66 +/- 14 pg/ml, respectively). The nafamostat group showed a significantly lower difference of CH50 assay results and malondialdehyde levels between coronary sinus blood and arterial blood and peak values of creatine kinase MB (43 +/- 12 IU/L versus 19 +/- 6 IU/L) during the postoperative course compared with findings in the control group. These results demonstrated that inflammatory reactions induced by cardiopulmonary bypass had adverse effects on myocardial recovery after aortic crossclamping and that nafamostat mesilate given during cardiopulmonary bypass appeared to reduce myocardial reperfusion injury by attenuating such inflammatory reactions. Attenuation of inflammatory reactions of cardiopulmonary bypass should be considered in the strategy of myocardial protection.

Benzamidines↗

PubMed1990

Development and evaluation of a rapid, semi-automatic micro-method for CH50 estimation using a computer program.

Established methods for the estimation of serum complement are often unsatisfactory. Problems include complex mathematical and/or technical manipulations, lack of objectivity, and poor sensitivity. Here we present an assay that is rapid, sensitive, quantitative, simple and semi-automatic by using an 'ELISA' reader to estimate released haemoglobin. It compares very favourable with a more manual, old established method. We have used this new method to establish a normal range, investigate serum storage conditions, and demonstrate that the sensitised sheep red blood cells are suitable targets after overnight storage at 4 degrees C. Furthermore we confirm that serum from patients with systemic lupus erythematosus or Sjögren's syndrome frequently has reduced levels of CH50. Patients with rheumatoid arthritis, scleroderma, Bechet's disease or arteritis have a mean CH50 within the normal range.

Complement Hemolytic Activity Assay↗

PubMed1995

An improved diagnostic assay for Lambert-Eaton myasthenic syndrome.

A new immunoprecipitation assay has been established for detecting antibodies to voltage-gated calcium channels (VGCCs) in Lambert-Eaton myasthenic syndrome (LEMS), using 125I-omega-conotoxin MVIIC, which binds to P-type VGCCs, to label extracts of human cerebellum. Fifty six of 66 serum samples (85%) from patients with clinically and electrophysiologically definite LEMS were positive for the presence of VGCC antibodies, defined as a titre > 3 SD above the mean for the healthy controls (n = 10). All disease controls (n = 40) were negative. This sensitive immunoassay should prove valuable in the diagnosis of LEMS.

Aged↗

PubMed1993

Red-cell bound anti-A is more efficient than anti-B in competition for fluid phase complement.

Lysis of group A and B erythrocytes by human complement was studied by an anti-A (BRIC.131) and an anti-B (BRIC.30) IgM monoclonal antibody in a 51Cr-release assay. The relative concentration of membrane-bound immunoglobulins was detected by flow cytometric analysis, and the amount of C1q and C3 bound to the sensitized red cells was measured by using purified, 125I-labelled molecules. The direct haemolysis was identical with both reagents in the presence of excess and suboptimal complement over a wide range of antibody concentration (between 50 and 7000 ng/ml). The indirect effect of membrane-bound antibody, i.e. its influence on complement binding by sensitized bystander cells, was examined in a cold target competition assay in which sensitized, non-labelled cells are present when complement is incubated with sensitized labelled cells. We have found that the competitive capacity of sensitized erythrocytes correlated with the amount of membrane-bound immunoglobulins. In accordance with our earlier findings, an equal level of target and competitor cell lysis was obtained only if the fluid phase anti-B antibody concentration was 2 to 4 times higher than that of the anti-A antibodies. We demonstrate in this paper that the different competitive activity of IgM anti-A and anti-B monoclonal antibodies might be accounted for by differences in their C1q and C3 binding capacities.

ABO Blood-Group System↗

PubMed1999

[Complement activation in citrate plasma--inhibitory effect of anticoagulants on serum complement activation].

It is generally accepted that complement activation does not proceed in EDTA- and citrate-plasma because of calcium chelation by EDTA and citrate. However, there were several cases with low CH50 level in serum and citrate plasma and normal CH50 level in EDTA plasma, suggesting that complement might be activated in citrate-plasma but not in EDTA-plasma. The present study deals with the inhibitory effect of EDTA and citrate on complement activation. CH50 was assayed in serum or plasma containing various concentrations of EDTA or citrate after incubation with latex particles bearing immunoglobulin. It was revealed that complement activation proceeded in the presence of 2.0 mmol/l of EDTA but was inhibited in the presence of 2.5 mmol/l of EDTA, while blood coagulation was inhibited in plasma containing EDTA higher than 2.0 mmol/l. As to citrate, complement activation proceeded in the presence of 25 mmol/l of citrate but was inhibited in the presence of 50 mmol/l of citrate, while blood coagulation was inhibited in plasma containing citrate higher than 6.2 mmol/l. Thus, it was indicated that, as usual plasma in clinic contains 3.5 mmol/l of EDTA or 10.9 mmol/l of citrate, complement can be activated in citrate-plasma but not in EDTA-plasma. Similar conclusion was obtained by another experiment using ordinary vacuum-type blood collection tube for EDTA-2K plasma, EDTA-2Na plasma and citrate plasma.

Anticoagulants↗

PubMed1992

The ontogenic and functional relationships between growth hormone- and prolactin-releasing cells during the development of the bovine pituitary.

The ontogeny of GH- and prolactin-releasing cells in the developing bovine pituitary was evaluated by reverse haemolytic plaque assays which allows for the detection of hormone release from individual pituitary cells in culture. With this approach, we observed that GH-releasing cells ontogenically preceded prolactin-releasing cells. In fact, GH secretors were observed as early as 59 days of gestational age while cells that released prolactin were not identified until 98 days. The amounts of both GH- and prolactin-releasing cells increased with time to reach more than 50% and 20% of all pituitary cells near term (term approximately 280 days) respectively. Interestingly, the first cells shown to release prolactin also released GH (i.e. were mammosomatotropes). This temporal and functional relationship between GH and prolactin secretors provides suggestive evidence that GH-secreting cells act as the progenitor cells for prolactin secretors via a functional intermediate, the mammosomatotrope.

Animals↗

PubMed1999

Sex-limited protein: in vitro and in vivo functions.

Mouse complement component C4 exists in two isoforms, C4 and a protein with expression restricted to male animals called sex-limited protein (Slp). Although Slp is about 95% homologous to C4, it is generally believed to be non-functional, at least in conventional haemolytic complement assays. In a previous study, however, we showed that Slp is haemolytically active in a C1-inhibitor (C1INH)-regulated, EDTA-resistant mouse complement activation pathway. To study other possible implications of this finding, we generated constitutively expressing Slp-transgenic mice. The transgene was crossed into otherwise Slp-deficient C57Bl/6J and NZB mice. Members of the third backcross generation of C57Bl/6J mice were tested for functional Slp and classical and alternative complement pathway activities (CH50 and AP50 levels, respectively). Slp-transgenic C57Bl/6J mice showed enhanced CH50, but normal AP50 levels when compared with non-transgenic littermates. To discover a possible protective role for Slp in spontaneous systemic lupus erythematosus (SLE) in NZBxNZW (NZBxW) mice, the third backcross generation of Slp-transgenic NZB mice was mated with NZW mice and the development of SLE in the female offspring was followed. In these introductory experiments, Slp-transgenic NZBxW animals presented with a significantly extended life span. Our results imply that Slp is a mouse complement component with functions which partially resemble some of those of human C4A.

Animals↗

PubMed1993

Why do patients develop reactions to streptokinase?

Minor reactions to streptokinase are not uncommon, although the etiology is unknown. It is widely presumed, however, that these, like the more serious immune reactions, are antibody-mediated. We measured specific anti-streptokinase IgG, subclasses IgG1, IgG2, IgG3, IgG4 and IgE by ELISAs, haemagglutination, indirect Coombs' test and immunoblotting in six patients who developed reactions to streptokinase. Evidence of complement activation by streptokinase was sought by a haemolytic complement assay and by measurement of C3, C4 and C3d. The patients who reacted to streptokinase presented with low titres of anti-streptokinase IgG (median = 5; range 0-32) and IgG1 (median = 3; range 0-14). No evidence of any other IgG subclass was found, nor of specific anti-streptokinase IgE. Anti-streptokinase IgG1 was found to fix complement; patients who reacted to streptokinase were found to have low levels of total complement 1 year post reaction. Probable aggregates and fragments of human albumin (added stabilizer) were found in the streptokinase preparation and proved to be antigenic in some patients, but were not found to be related to the development of reactions. The findings suggest that patients who develop reactions to streptokinase cannot be predicted on the basis of antibody titres at presentation. Minor reactions to streptokinase would not appear to be antibody-mediated, although complement activation may be involved.

Aged↗

PubMed1994

Coxsackie B1 virus-induced murine myositis: a correlative study of muscular lesions and serological changes.

We investigated the role of humoral factors in the pathogenesis of Coxsackie B1 virus-induced murine myositis (CB1-myositis). At 2, 4 and 8 weeks after inoculation, serum was studied for circulating immune complexes (CIC) (Raji-cell assay), haemolytic complement activity (CH50 titre) and anticytoplasmic autoantibodies (Western blotting, immunoprecipitation) in relation to degree of mononuclear cell infiltration and muscle fibre necrosis. At 2, 4 and 8 weeks, cell infiltration correlated positively to muscle fibre necrosis. From 2 weeks on, moderate quantities of CIC were found in nearly all CB1-inoculated mice, but without correlation to histological changes. Except for a positive correlation of CH50 titre to muscle necrosis at 4 weeks (r = 0.60; P = 0.02), CH50 titres did not correlate to muscle lesions. Anticytoplasmic and other known autoantibody specificities were absent. In conclusion, first, in CB1-myositis CIC occurred from 2 weeks on, but no correlative evidence was found for their involvement in pathogenesis, neither for that of complement nor for anticytoplasmic autoantibodies. Secondly, cell infiltration correlated positively to muscle necrosis, underscoring the importance of cellular mechanisms. Thus, our data do not support, or conclusively exclude, a role for humoral processes in CB1-myositis.

Animals↗

PubMed1994

The susceptibility of S-layer-positive and S-layer-negative Aeromonas strains to complement-mediated lysis.

Forty strains of Aeromonas hydrophila and Aeromonas veronii recovered from invasive and non-invasive infections were tested for their susceptibility to complement-mediated lysis by 65% pooled human serum (PHS). Based upon the results of this assay, two major populations could be defined. The first group (n = 20) consisted of serogroup O:11 strains, all of which possessed a paracrystalline surface layer (S layer); all of these strains were refractory to the bactericidal activity of 65% PHS with the exception of A. hydrophila strain AH-121, which was composed of mixed subpopulations of serum-susceptible and serum-resistant clones. A second collection of isolates (n = 20), all of which were S-layer-negative, contained a subgroup of strains (n = 7) that were highly susceptible to complement-mediated lysis, showing a greater than 100-fold reduction of viable progeny within 30 min of exposure to 65% PHS. Serum-resistant strains from both groups could not be lysed by exposure of bacterial cells to polyclonal somatic or whole cell antisera or to 30 micrograms ml-1 of polymyxin B nonapeptide prior to challenge with 65% PHS. Analysis of selected serum-resistant and serum-susceptible strains from both groups showed that all isolates activated the complement pathway and most bound C3b to the cell surface, indicating that the inability of complement to lyse serum-resistant strains was related to a defect in the terminal portions of the complement pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Aeromonas↗

PubMed1983

A sensitive microassay for the determination of hemolytic complement activity in bovine milk.

A 51Cr release microhemolytic complement assay is described to detect hemolytic complement activity in bovine milk. 51Cr-labeled guinea-pig erythrocytes (GPRBC), which have been sensitized with a subagglutinating amount of rabbit anti-GPRBC, are placed in microtiter plates. Pooled bovine sera as source of complement to achieve about 50% of 51Cr release were added to each well prior to the addition of the samples on the test. Determination of CH100 titer was obtained by difference of counting between heated and unheated diluted whey samples from a standard linear regression. Comparative hemolytic values throughout lactation were established for the first time and confirmed the improved sensitivity of the assay.

Animals↗

PubMed1991

Kinetics of the biosynthesis of complement subcomponent C1q by murine macrophages: effects of stimulation by interferon-gamma.

The effects of interferon-gamma (IFN-gamma) on the kinetics of biosynthesis of complement subcomponent C1q by mouse inflammatory peritoneal macrophages were determined. Stimulation of macrophages with various concentrations of IFN-gamma produced a dose-dependent increase in C1q mRNA accumulation which was detected as early as 3 h and sustained through 24 h, as determined by Northern blot analysis. A corresponding early increase in the extracellular accumulation of functional C1q was detected in culture supernatants after 3-9 h stimulation of macrophages with IFN-gamma that was sustained for 24-48 h as determined by a complement hemolytic assay. Autoradiographic analysis of [35S]methionine-labeled secretory C1q confirmed the protracted dose-dependent secretion of C1q by IFN-gamma stimulated macrophages during 24-48 h of culture. Western blot analysis of macrophage lysates indicated no significant changes in endogenous C1q levels following stimulation with IFN-gamma either after 3-9 h or 24-48 h when both C1q mRNA and extracellular accumulation were at their peak. Our results indicate that IFN-gamma promotes early and protracted mRNA accumulation and secretion of C1q by macrophages without intracellular accumulation, presumably due to the rapid rate of secretion of newly synthesized C1q. It is apparent that priming of macrophages with IFN-gamma provides a rapid and abundant source of secretory C1q for potential interaction with various macrophage triggering agents which also bind C1q.

Animals↗

PubMed1992

Discordant secretion of relaxin by individual porcine large luteal cells: quantitative analysis by a reverse haemolytic plaque assay.

Individual large luteal cells (LLC) derived from pregnant swine differ conspicuously in their ability to secrete the peptide hormone relaxin under basal and stimulated conditions--the phenomenon of functional heterogeneity. The purpose of this study was to quantitate knowledge of this phenomenon through use of a reverse haemolytic plaque assay, a technique that utilizes antibody-directed, complement-mediated erythrocyte lysis to detect hormone secretion by single LLCs in culture. Measurement of individual plaque areas (an index of the amount of relaxin secreted) demonstrated an approximate 100-fold range in the amount of relaxin secreted by a single cell under basal conditions. This range was doubled by exposure to the phorbol ester, 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA; 50 nmol/l). Under basal conditions, 50 and 80% of the total amount of relaxin was secreted by approximately 10 and 30% of all LLCs respectively. The size of these fractions was not influenced by the time of incubation (1-8 h), or by the presence of either of two non-specific stimulatory relaxin secretagogues, PMA (50 nmol/l) or arachidonic acid (1 mumol/l). The unimodal frequency distribution of plaque areas (under basal or stimulated conditions) suggests that relaxin-secreting LLCs comprise a discrete functional population of secretory cells, at least under these experimental conditions. We conclude that a remarkably small fraction of LLCs secretes the majority of relaxin, and that the size of this fraction was not influenced by time or secretagogues.

Animals↗