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Results for “Complement C3”

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At least 937 records · Page 52Linked to original sources

PubMed1983

C3d receptors are expressed on human monocytes after in vitro cultivation.

Highly purified human third component of complement (C3) was used to coat sheep erythrocytes (E) that were sensitized with IgM antibody (EA), forming EAC3b over a wide range of C3 molecules per cell. EAC3b were converted to EAC3bi by incubation with purified C3b inactivator (factor I) and beta 1H globulin (factor H). EAC3bi were in turn trypsinized to produce the cellular intermediate EAC3d. Each of the cell types was carefully characterized to be certain of the type of C3 determinant expressed. These cellular complement intermediates were used to assess by rosette formation the C3 receptor activity on peripheral blood monocytes under various experimental conditions. Uncultivated monocytes from peripheral blood bound EAC3b and EAC3bi well but did not bind EAC3d significantly. However, upon cultivation on glass surfaces in the presence of fetal calf serum but not bovine serum albumin, monocytes showed a progressive increase in expression of the C3d receptor. The Fab' fragment of anti-C3c blocked binding of EAC3b completely, blocked EAC3bi partially, but failed to block binding of EAC3d to cultivated monocytes. In contrast, the Fab' fragment of anti-C3d blocked EAC3d rosette formation completely. These studies demonstrate that monocytes are capable of expressing receptor activity for a determinant on C3d but that the expression of this receptor depends on the state of activation or differentiation of the cells.

Cell Differentiation↗

PubMed2002

Alterations in immune parameters in foundry and pottery workers.

To assess the immune competence of workers occupationally exposed to mainly silica, peripheral blood lymphocytes, serum immunoglobulins (IgG, IgA and IgM), C3 and C4 complement protein concentrations of foundry and pottery workers were evaluated and compared to healthy controls with no history of silica and other chemical exposure. The absolute number and percentage of functionally different subsets of peripheral blood mononuclear lymphocytes, i.e. T, T-suppressor and natural killer cells were unchanged. However, T-helper lymphocytes in pottery (P<0.05) and B cells in foundry (P<0.01) workers were significantly lower when compared to their controls. In addition, silica-exposed foundry workers had a significant reduction in the IgG, IgA and IgM levels. No significant differences were observed in the serum complement C3 and C4 levels of the workers. These results suggest that human chronic exposure to mainly silica and other chemicals originating from foundry and pottery settings may be detrimental to the immune system.

Adolescent↗

PubMed2002

[Effect of Chinese drugs mixture on immune function of patients with extremely severe burn].

OBJECTIVE: To study the regulatory effect of Qinghuo Baidu Yin (QHBDY, a mixture prepared with Chinese drugs) on immune function of patients with extremely severe burn (ESB). METHODS: Thirty patients with ESB were divided into two groups, conventional therapy was given to both groups, but QHBDY was given to the treated group additionally. Immunological indices, including peripheral blood T-lymphocyte subsets, immunoglobin (IgG, IgA and IgM) and complement (C3 and C4) were determined 3 weeks after treatment to evaluate and compare the therapeutical effect in the two groups. RESULTS: Compared with the control group, CD3, CD4, CD4/CD8, immunoglobin (IgG, IgA and IgM) and complement (C3 and C4) levels were markedly decreased in degree, and recovered earlier and quicker, with CD8 increased mildly (P < 0.01) and turned back more quickly. And so did the parameters of the treated group in comparing with that of the control group at anytime (P < 0.05 or P < 0.01). CONCLUSION: Chinese drugs mixture shows the regulatory effect on both cellular and humoral immune function in patients with ESB.

Adjuvants, Immunologic↗

PubMed1977

[Effects of diphtheria and tetanus toxins on liver regeneration in the rat].

The effects of diphtheria toxin and tetanus toxin on the regenerating rat liver were studied. The following parameters were used: liver regeneration percentage, mitotic index, protein content and serum complement C3 fraction level. Diphtheria toxin does not affect the liver regeneration, that what confirms the poor sensitivity of the rat to this toxin. Tetanus toxin inhibits the cellular division, while causes an increase in the cell protein content, resulting in hepatocyte hypertrophy. Both toxins cause a fall of the serum complement C3 fraction.

Animals↗

PubMed1989

Enhancing effect of antitumor polysaccharide from Astragalus or Radix hedysarum on C3 cleavage production of macrophages in mice.

Effects of Astragalus polysaccharide (APS) and Radix hedysari polysaccharide (RHPS) on the third component of complement (C3) cleavage production of macrophages in ICR mouse were investigated by the immunofluorescent method. By two hours after intraperitoneal injection of 500 mg/kg of APS or RHPS, there was an obvious increase in the deposition of C3 on peritoneal macrophages. When APS or RHPS was injected 5 times (1 time/day), the proportion of C3 positive macrophages was more than that of 1-time injection. At the same time, the number of peritoneal macrophages also increased. Since C3 cleavage product occurred with the activation of C3, the results suggest that the immuno-potentiating action of APS and RHPS may be related to the activity of mouse complement C3.

Animals↗

PubMed1979

The C3 component of complement; gene frequency variation in Iraq.

Heterogeneity of gene frequencies in the polymorphism of the third component of complement among local samples in Iraq is analysed. It appears to derive essentially from population and not from regional differences.

Complement C3↗

PubMed1975

Vitamin A in liposomes. Inhibition of complement binding and alteration of membrane structure.

Incorporation of vitamin A aldehyde (retinal) into liposomes had an inhibitory effect on the amount of human complement protein bound in the presence of specific antiserum. The total membrane-bound protein was directly measured on liposomes which were washed after incubation in antiserum and fresh human serum (complement). At every concentration of complement, decreased protein binding was found with liposomes which contained retinal. Binding of the third component of complement (C3) was also measured directly on washed liposomes and was found to be decreased in the presence of retinal. The diminution in protein binding due to retinal was not caused by differences in the amount of antibody bound and this was shown by two experiments. First, specific antibody protein binding to liposomes was directly measured and was essentially unaffected by retinal. Second, liposomes were prepared from lipid extracts of sheep erythrocytes. These liposomes were used as as immunoadsorbants to remove antisheep erythrocyte antibodies. The immunoadsorbant capacity was the same in both the presence and the absence of retinal. A further conclusion from these experiments was that retinal did not change the number of liposomal glycolipid antigen molecules available for antibody binding and thus presumably did not change the total number of lipid molecules present on the outer surface of the liposomes. Retinal did have an effect on the geometric structure of the liposomes. Size distribution measurements were performed in the diameter range of 1-6.35 mum by using an electronic particle size analyzer (Coulter Counter). Liposomes containing retinal were shifted toward smaller sizes and had less total surface area and volume. It was suggested that retinal-containing liposomes may have had a tighter packing of the molecules in the phospholipid bilayer. This effect of retinal on liposomal structure may have been responsible for the observed decreased binding of C3 and total complement protein.

Animals↗

PubMed1987

Protein metabolism in obese patients during very low-calorie mixed diets containing different amounts of proteins and carbohydrates.

To assess long-term nitrogen sparing capacity of very low-calorie mixed diets, we administered two isoenergetic (2092KJ) liquid formula regimens of different composition for 8 weeks to two matched groups of massively obese patients (group 1: proteins 60 g, carbohydrate 54 g; group 2: proteins 41 g, carbohydrates 81 g). Weight loss was similar in both groups. Daily nitrogen balance (g) during the second month resulted more a negative in group 2 with respect to group 1. However, within the groups individual nitrogen sparing capacity varied markedly; only a few in group 1 and one in group 2 were able to attain nitrogen equilibrium throughout the study. Daily urine excretion of 3-methylhistidine fell significantly in group 1 but did not change in group 2. Unlike total proteins, albumins, and transferrin, serum levels of retinol-binding protein, thyroxin-binding globulin, and complement-C3 fell significantly in both groups but per cent variations of complement-C3 were more pronounced in the first group. Prealbumin levels fell persistently in group 1 and transiently in group 2. The results indicate that even with this type of diet an adequate amount of dietary protein represents the most important factor in minimizing whole body protein catabolism during long-term semistarvation in massively obese patients. Moreover, they confirm the possible role of dietary carbohydrates in the regulation of some visceral protein metabolism.

Adult↗

PubMedDate not supplied

Peptidergic pathway in human skin and rat peritoneal mast cell activation.

The common pathway of heterogenous mast cell activation as mediated by antigens is through the cross-linking of IgE bound to Fc epsilon RI receptors. The peptidergic pathway of mast cell activation, achieved by cationic secretagogues, is restricted to "serosal" mast cells, the experimental models being rat peritoneal and human skin mast cells. Cationic secretagogues include positively charged peptides but also various amines such as compound 48/80 and natural polyamines. An early intracellular event of this pathway is the activation of pertussis toxin-sensitive G proteins. The correlation observed between the ability of basic compounds to trigger mast cell exocytosis and their potency to activate purified G proteins strongly suggests that cationic compounds activate mast cell G proteins via a receptor-independent but membrane-assisted process. In this paper, alternative mechanisms are discussed. The consequence of G protein stimulation is the activation of phospholipase C with an increase in inositol triphosphates. Natural polyamines are relatively poor triggers of mast cells (10(-4) to 10(-2) M). Neuropeptides such as substance P, neuropeptide Y or vasoactive intestinal peptide, peptidic hormones such as kinins, and venoms such as mastoparan and mast cell degranulating peptide, are all active in a concentration range from 10(-7) to 10(-4) M. The cationic anaphylatoxin C3a also stimulates mast cells at concentrations below precursor complement C3 blood levels. The component C3 of the complement system is one of only a few plasma proteins having activation fragments (i.e. C3a) that can be generated at micromolar levels. The effects of basic secretagogues defines a peptidergic pathway of mast cell activation, which represents a potentially toxic process considering the tissue effects caused by exogenous basic compounds such as venom peptides and certain amine containing drugs. Peptidergic activation of mast cells may also be a pathophysiological process having an important role in neurogenic inflammation and in diseases involving extensive activation of the blood complement cascade.

Amino Acid Sequence↗

PubMed1976

Leucocyte function in a case of chronic benign neutropenia of infancy associated with circulating leucoagglutinins.

A case of chronic benign neutropenia is described in association with circulating leucoagglutinins. IgG and IgM leucoagglutinins demonstrated by Sephadex G-200 chromatography agglutinated neutrophils and monocyte enriched leucocyte preparations. Total IgG, IgA, IgM and IgE, total haemolytic complement, C3 and C4 complement components were all within normal limits. Lymphocyte populations and transformation were normal apart from a relative increase in the number of B lymphocytes. In vitro studies showed that the patient's monocytes responded in chemotaxis, phagocytosis and intracellular killing of S. aureus in a comparable fashion to that of control neutrophils. Although the patient's serum also agglutinated monocytes these findings do not exclude the possibility that leucoagglutinins may have aetiological significance in this disease. The study also emphasizes the versatility of the monocyte in benign neutropenia.

Agglutinins↗

PubMed1986