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PubMed1976

Inhibition of the alternative pathway of complement activation by a serum factor generated during transplant rejection.

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Complement C3↗

PubMed1977

Role of complement in thrombogenesis. I. Complement-dependent coagulation in a model system.

Chondroitin sulphate was used to isolate from plasma a system that clotted with Russell's viper venom, brain extract and activated contact factors. Clotting appeared to depend on concomitant change in C4, C3 and C1s in the system. Brain extract additionally reacted with C9. Reconstitution of specifically defective plasmas suggested a specific role for each of these complement components in clotting.

Antigen-Antibody Reactions↗

PubMed1988

Detection of the terminal complement complex in patient plasma following acute myocardial infarction.

The mechanisms of inflammation responsible for the myocardial tissue damage seen after an acute myocardial infarction (AMI) have not been clearly identified. Recent lines of evidence, demonstrating depressed sera levels of individual complement components in patients after myocardial infarction, have suggested involvement of the complement (C) system in micro- and macrovascular injury subsequent to AMI. The present study assessed the role of complement as a mediator of myocardial inflammation by quantifying products of complement activation including, the terminal complement complex (TCC) the cytolytic component of the complement system, C1rC1s-C1 inhibitor complex and C3bBbP complex, formed following activation of the classical and alternative pathway, respectively, and anaphylatoxins C3a and C5a in 41 patients following AMI. Plasma TCC and C1rC1s-C1 inhibitor complex concentrations increased up to 32-fold (P less than 0.001) and 8-fold (P less than 0.001), respectively, while the C3bBbP complex, C3a des-Arg and C5a des-Arg each increased over 2-fold (P less than 0.001) 16 h after AMI, and were only minimally detectable during non-inflammatory myocardial conditions. Furthermore, TCC concentrations increased over 150% (P less than 0.001) one day after patients reinfarcted, subsequent to hospitalization for a primary AMI. These results demonstrate activation of complement after AMI and suggest that inflammatory mediators of the complement system may contribute to myocardial tissue damage during the infarction process.

Adult↗

PubMed1979

Quantitation of the membrane attack complex of complement in an air-driven ultracentrifuge.

A sensitive assay of complement (C) activation via either the classical or alternative pathway was developed by evaluating assembly of the terminal complexes (C5b-9)2 or SC5b-9. Activation of serum containing [125I]C7 resulted in the formation of a stable, radiolabeled complex which was separable from its precursors by sedimentation in an air-driven ultracentrifuge. The radioactivity in the sediment was directly proportional to the amount of complex formed and assembly of the complex could be detected after C activation by aggregated IgG in concentrations as low as 10 micrograms/ml. Mild detergents such as Triton X-100 could be included in the reaction mixture, because they affected neither the assembly nor the integrity of the complexes. The assay, which detects both assembly of the membrane attack complex (MAC or (C5b-9)2) on target membranes and formation of SC5b-9 in fluid phase, measures the potential of certain substances to trigger the cytolytic phase of C regardless of whether the classical or alternative pathway was activated. However, by using serum depleted of either factor B or C1q, activation of either pathway can be assessed individually.

Cell Membrane↗

PubMed1982

Purification of human C5a des arg by immunoadsorbent and molecular sieve chromatography.

Human C5a des arg was isolated from complement-activated serum by immunoadsorption followed by Sephadex G-75 chromatography. C5a des arg obtained by this 2-step procedure was shown to be immunologically identical to C5a des arg purified by a conventional multi-step method, homogeneous on SDS-polyacrylamide gels, and biologically active. Although this technique yields approximately the same amount of C5a des arg/liter of activated serum as that obtained by conventional methods, its simplicity and relative rapidity make it a practical alternative.

Animals↗

PubMed1985

Electroimmunoassay-immunoblotting (EIA-IB) for the utilization of monoclonal antibodies in quantitative immunoelectrophoresis: the method and its applications.

Immunoprecipitates formed in conventional electroimmunoassays were solubilized by brief immersion of the agarose gels in sodium dodecylsulfate. The proteins were then transferred to nitrocellulose sheets by electroblotting. The blotted proteins were readily amenable to analyses by non-precipitating monoclonal antibodies and the immunoblots were developed with second antibody/biotin-streptavidin-peroxidase staining. The electroimmunoassay-immunoblot (EIA-IB) method is of value in (1) specificity assays of monoclonal antibodies in crossed immunoelectrophoresis; (2) analysis of specific molecular interactions between proteins; (3) rapid screening and simple identification of monoclonal antibodies by line immunoelectrophoresis-immunoblotting.

Animals↗

PubMed1989

1H nuclear magnetic resonance assignments and secondary structure of porcine C5ades Arg.

Sequence-specific assignments of the 1H nuclear magnetic resonance spectrum of porcine C5ades Arg are described. Assignments were facilitated by comparison of spectra obtained in H2O with partially exchanged spectra obtained in 2H2O. The sequence-specific assignments thus obtained were used to characterized the regular secondary structure in the protein, which is helical in the regions 2 to 11, 16 to 27, 35 to 41 and 45 to 64. The structure is very similar to that of human and bovine C5a.

Amino Acid Sequence↗

PubMed1985

Regulation of monocyte function by complement activation products.

Normal human monocytes, obtained at a mean purity of 60% by Percoll density gradient centrifugation, were found to be chemotactically deactivated to C5a by exposure to low, and biologically significant, concentrations of zymosan-activated serum (ZAS), while retaining their full response to FMLP. C5a was found to be 40X more potent than its metabolite C5adesArg in reducing chemotaxis to activated pooled serum. Conversely, exposure of monocytes to varying concentrations of N-formyl-methionyl-leucyl-phenylalanine (FMLP) decreased chemotaxis to that attractant, though had no effect on chemotaxis to activated serum. Monocytes were also found to actively absorb C5a from solutions of ZAS, rich in C5a. Our data support the concept that monocytes are specifically regulated by C5a and C5adesArg.

Blood↗

PubMed1989

Anaphylatoxin generation in acute pancreatitis.

Fifty-one patients with elevated serum amylase and clinical signs of acute pancreatitis were studied prospectively. The concentrations of anaphylatoxins (C3a and C5a) were measured with a radioimmunoassay and the activity of their inactivator was determined. The pancreatitis was classified as mild, moderate, or severe according to Ranson's 11 signs, appearance of peritoneal fluid, and development of multisystem organ failure (MSOF). Plasma C3a and C5a concentrations were elevated during attacks of acute pancreatitis. Anaphylatoxin levels correlated with the severity of the disease (C3a, P less than 0.001; C5a, P less than 0.05). The highest and most persistent levels were found in the group with MSOF. C3a levels decreased rapidly during recovery. In patients with complications like abscess or pseudocyst, the C3a elevation persisted until adequate treatment was instituted. In this study, no significant changes of the inactivator levels were found, except at discharge when the inactivator level of the severe group was elevated compared to that of the moderate and mild groups (P less than 0.05).

Acute Disease↗

PubMedDate not supplied

Interaction of human beta-endorphin with the terminal SC5b-9 and "preterminal" SC5b-7 and SC5b-8 complexes of human complement.

Human beta-endorphin (beta H-EP) is demonstrated to bind to the "preterminal" SC5b-7 and SC5b-8 complexes and to the terminal SC5b-9 complex of human complement. Detailed binding studies revealed saturability, reversibility and structural specificity of the beta H-EP interaction with high or low affinity non-opiate binding sites on SC5b-7 and SC5b-9 complexes. The high affinity binding sites seem to be located predominantly on C5b, C6 or C7 subunits of the complexes.

Alpha-Globulins↗

PubMed1983

Neutrophil activation as a mechanism of tissue injury.

C5A is capable of causing granulocyte/granulocyte interactions that lead to clumping, vasoocclusion, and the extension of infarctive damage in patients with coronary artery disease. Employing a new rheologic procedure, laser transillumination of thin vascular beds, one directly observes in vivo granulocyte aggregation in the mesentery of the rat. Nonsteroidal antiinflammatory drugs (NSAIDs) were shown to stop granulocyte agglomeration and to limit the extension of experimental myocardial infarcts in the cat. There may be application for NSAIDs for myocardial infarction in humans. NSAIDs block granulocyte aggregation to both a traditional activated complement and a complement activated by cryoglobulins. Patients with severe cryoglobulinemic cutaneous vasculitis who failed on steroids responded to NSAID administration.

Animals↗

PubMed1984

Inflammatory mediators stimulate granulocyte adherence to cultured human endothelial cells.

The factors that regulate the adherence of granulocytes to the endothelium under normal conditions, and in states of inflammatory vascular injury, are largely unknown. We found that treatment of primary, confluent monolayers of human umbilical vein endothelial cells with inflammatory mediators (zymosan-activated plasma, as a source of C5a fragments, and N-formylmethionyl-leucyl-phenylalanine) stimulated granulocyte adherence to the monolayers. The augmented adherence was dose-, time-, and temperature-related and demonstrated kinetics characteristic of the adherence of single cells with increased affinity for monolayer cultures. Adherence stimulated by the inflammatory mediators was not prevented by washing the monolayers after treatment with the mediator. Human albumin diminished both spontaneous and stimulated adherence, although the relative increase in adherence stimulated by the inflammatory mediator was unchanged. Calcium and magnesium were required for stimulated adherence. These data suggest that inflammatory mediators may bind to, or directly alter, human endothelial cells resulting in enhanced granulocyte adherence, and define characteristics of this endothelial cell-granulocyte interaction.

Cell Adhesion↗

PubMed1987