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Results for “Complement Inactivator Proteins”

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At least 397 records · Page 22Linked to original sources
PubMed1997

Measurement of anticomplementary activity in therapeutic intravenous immunoglobulin preparations.

Anticomplementary activity (ACA) of aggregates in intravenous immunoglobulin preparations (IVIG) was investigated using the modified Kabat and Meyer classical complement consumption method recommended by the European Pharmacopoeia and a C1q-coated microtitre enzyme-linked immunosorbent assay (ELISA). The physical characteristics of aggregates were found to affect complement binding. Aggregates formed by heating IVIG preparations at acid pH bound complement poorly, while aggregates formed by heating IVIG at neutral pH showed high ACA. This suggests that analysis of complement binding capacity provides a level of aggregate characterization of aggregates which is additional to quantitation by High-performance liquid chromatography ((HPLC). The correlation (r = 0.98) between the two tests was good when aggregates formed at neutral pH were compared, but decreased (r = 0.57) when aggregates formed at acid pH were included. A comparison of the results showed that there were no significant differences in the classification of aggregates with acceptable/unacceptable (i.e. pass/fail outcome) values of ACA. Between assay variation (CV = 7.6%) was lower in the ELISA test compared with the complement consumption assay (where percentage binding varied from 78.9% to 100%). Both assays are justified for the evaluation of ACA in therapeutic IVIG. The ELISA had the advantage in being more precise, less dependent on reagent source and requiring less technical expertise.

Complement Inactivator Proteins↗
PubMed1999

Cytotoxicity by stored human breast-milk: possible contribution of complement system.

Human milk stored over some period in vitro possesses certain cytotoxic properties, which require further studies. Cytolysis induced by stored human milk has now been further characterized, using rabbit red blood cells as targets, to determine the contribution of other components, particularly the complement system. Cytolysis was found to be temperature dependent, greatly enhanced by low concentrations of magnesium and calcium ions, but inhibited by moderate to excessive amounts of calcium ions, and by heating at 56 degrees C.

Animals↗
PubMed2001

Effect of macrophages and serum of fish susceptible or resistant to epizootic ulcerative syndrome (EUS) on the EUS pathogen, Aphanomyces invadans.

Epizootic ulcerative syndrome (EUS) is one of the most destructive diseases of fresh and brackish water farmed and wild fish in the Asia-Pacific region. The in vitro germination and growth of the propagules of the EUS pathogen, Aphanomyces invadans (= A. piscicida), were assessed in the presence of the head-kidney macrophages, serum, and serum heated to inactivate complement proteins, of three EUS-susceptible and one resistant fish species. The susceptible species were: striped snakehead (Channa striata), giant gourami (Osphronemus gouramy) and silver barb [Barbodes (= Puntius) gonionotus], and the resistant species was Nile tilapia (Oreochromis niloticus). Fish of all species were acclimatised to either low temperature (20 degrees C +/- 1.6) at which EUS is known to occur, or to high temperature (32 degrees C +/- 5.0) at which EUS does not occur, except for giant gouramis which were only studied at low temperature. The respiratory burst of the macrophages was assessed in the presence of A. invadans or the stimulant phorbol myristate acetate (PMA), and compared to that of controls. Anti-A. invadans antibody concentrations were assessed in all species except silver barbs. All assays were carried out at the same temperature, regardless of the temperature that the fish were kept at. Macrophages of all species other than snakeheads inhibited fungal germination at both temperatures, though only silver barb and gourami macrophages could inhibit germling growth. PMA increased the respiratory burst in nearly all cases. The respiratory burst in the presence of A. invadans was consistently lower than that of controls, though the difference was only significant in the case of snakeheads. The respiratory burst of all macrophage treatments was higher at a low temperature. Except in the case of PMA-stimulated macrophages, regressions between respiratory burst and inhibitory action were only found in susceptible species, suggesting that the respiratory burst is important in those species, but is unable to prevent the proliferation of A. invadans. Serum inhibited fungal germination in all cases other than low temperature tilapia, indicating that the EUS resistance of tilapia is not due to the serum. Inhibition of germling growth by serum only occurred in silver barbs and gourami. Heated serum did not inhibit germination in any case except that of high temperature snakehead, and in fact stimulated germination in the case of tilapia. Heating serum did not affect the growth inhibiting activity of silver barbs and gouramis, but it stimulated growth in some groups. At high temperatures snakeheads had high anti-A. invadans antibody concentrations, which may explain the inhibitory activity of their heated serum. A role for complement and antibodies in defence against A. invadans in susceptible species is suggested.

Animals↗
PubMed1993

C4BPAL1, a member of the human regulator of complement activation (RCA) gene cluster that resulted from the duplication of the gene coding for the alpha-chain of C4b-binding protein.

The regulator of complement activation (RCA) gene cluster evolved by multiple gene duplications to produce a family of genes coding for proteins that collectively control the activation of the complement system. We report here the characterization of C4BPAL1, a member of the human RCA gene cluster that arose from the duplication of the C4BPA gene after the separation of the rodent and primate lineages. C4BPAL1 maps 20 kb downstream of the C4BPA gene and is the same 5' to 3' orientation found for all RCA genes characterized thus far. It includes nine exon-like regions homologous to exons 2-8, 11, and 12 of the C4BPA gene. Analysis of the C4BPAL1 sequence suggests that it is currently a pseudogene in humans. However, comparisons between C4BPAL1 and the human and murine C4BPA genes show sequence conservation, which strongly suggests that, for a long period of time, C4BPAL1 has been a functional gene coding for a protein with structural requirements similar to those of the alpha-chain of C4b-binding protein.

Animals↗
PubMed1997

Role of complement in rats injected with liposome-encapsulated hemoglobin.

Previous studies have documented that liposome-encapsulated hemoglobin (LEH) can cause a rapid and transient thrombocytopenia following intravenous injection into small animals. The present study evaluated the role of complement during the LEH-induced thrombocytopenia in rats. We have compared changes in platelet levels in the blood, platelet organ distribution, and total hemolytic complement levels following intravenous administration of LEH in control and complement-depleted rats. Changes in platelet organ distribution at various times after LEH administration were monitored by labeling autologous platelets with indium-111 (111In)-oxine and imaging the 111In-platelets with a gamma camera after reinjection. Platelet counts were determined by light-scattering methods and by following 111In radioactivity at various times after LEH administration. Platelet levels did not significantly change for the complement-depleted rats during the 60 min following an injection of LEH, whereas thrombocytopenia (40% decrease) was noted within 4 min post-LEH-injection for control rats with a gradual return to baseline circulating platelet levels within 60 min. This drop in circulating platelets was correlated with a rapid redistribution of 111In-platelets from the circulation to the lungs and liver, whereas complement-depleted rats showed no transient movement of the 111In-platelets from the circulation. Baseline complement levels of 21.6 +/- 2.2 CH50/ml for control rats and 0.2 +/- 0.1 CH50/ml for complement-depleted rats did not significantly change during the 60 min following LEH administration. This study suggests that complement must be present during LEH-induced transient thrombocytopenia, as complement-depleted rats underwent no thrombocytopenia, and that the transient LEH-induced thrombocytopenia may be associated with complement activation.

Animals↗
PubMed1993

Reintroduction of gene(s) into an attenuated deletion mutant of vaccinia virus strain IHD-W.

To evaluate individual genes responsible for virulence of vaccinia virus, a shuttle vector containing a viral fusion fragment from a deletion mutant (Z-19) was constructed. The vector also included a beta-galactosidase cassette which contained the LacZ under the control of the vaccinia late promoter p11 to screen recombinants. The gene in question was reinserted into the attenuated mutant by homologous recombination. The vaccinia growth factor and the vaccinia complement-binding protein genes were inserted into this shuttle vector and transferred by recombination into Z-19. The presence of the inserted gene was examined by Southern hybridization and its expression by Northern blot hybridization. The virulence of the recombinants was investigated by inoculation into mice. Results indicate that the recombinants contained and expressed the inserted gene. Although virulence was recovered, it did not reach the level of the wild-type, either when the recombinant viruses were inoculated alone or in combination. Construction of the shuttle vector allows reintroduction of genes into Z-19 which is completely attenuated in vivo and could be useful as a vaccine vector.

Animals↗
PubMed2000

Alzheimer disease and neuroinflammation.

It is now generally accepted that the lesions of Alzheimer disease (AD) are associated with a host of inflammatory molecules, including complement proteins, as well as with many activated microglia. Most inflammatory components are synthesized by brain cells. In order to estimate the intensity of the inflammatory reaction, we have measured the levels of the mRNAs for complement proteins, two complement regulators (CD59 and C1 inhibitors), an acute phase reactant (C-reactive protein, CRP) and two microglial markers, (HLA-DR and CD11b), in normal and AD brain. The mRNAs for inflammatory mediators are markedly upregulated in AD tissue while those of the complement inhibitors are almost unchanged. The upregulations for CRP and CD11b in AD hippocampus are comparable to those in osteoarthritic joints. This lends further support to the hypothesis that chronic inflammation may be causing neuronal death in AD.

Alzheimer Disease↗
PubMed1992

Protective effect of 16,16-dimethyl prostaglandin E2 on isolated rat hepatocytes against complement-mediated immune attack.

16,16-Dimethyl prostaglandin E2 was examined for its ability to inhibit complement-mediated in vitro hepatocytolysis by an antigen-antibody reaction. In the presence of fresh rat serum as a source of complement, 5-min culture of isolated rat hepatocytes with a monoclonal antibody against a rat liver-specific membranous antigen resulted in a marked, significant elevation in lactate dehydrogenase leakage into the culture medium. However, with heat-inactivated rat serum, such a reaction did not occur, indicating that the hepatocytolysis induced by the antibody was attributable to the membrane damaging action of complement activated by an antigen-antibody reaction. Pretreatment of the hepatocyte with 16,16-dimethyl prostaglandin E2 significantly suppressed the cytolytic reaction induced by the antibody in a concentration-dependent manner. These results show that 16,16-dimethyl prostaglandin E2 is capable of protecting isolated rat hepatocytes against the membrane-damaging insult of activated complement.

16,16-Dimethylprostaglandin E2↗
PubMed1987

Carbohydrate interference of complement-dependent cell lysis.

The antibody-mediated cytotoxicity of three autoreactive sera, an allogeneic hyperimmune serum and a xenogeneic hyperimmune serum was abrogated by the presence of either glucosamine, galactosamine, lactulose or lactose. This inhibition could be overcome in a dose-dependent fashion by increasing the amount of complement in the cytotoxicity assay, but not by increasing the amount of antibody. Furthermore, the inhibition was specific for these sugars in that isomers and N-acetylated derivatives were not inhibitory. The results suggest that these sugars directly blocked events of the complement cascade.

Animals↗