Class immunoglobulins and complements (C3 & C4) in Egyptian form of cutaneous leishmaniasis.
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Adult↗
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Results for “Complement C3”
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Expression of the third component of complement, C3, in regenerating limb blastema cells of urodeles.
In this study we have shown that complement component C3 is expressed in the regenerating tissue during urodele limb regeneration. C3 was expressed in the dedifferentiated regeneration blastema and in the redifferentiated limb tissues in the axolotl, Amblystoma mexicanum, and in Notophthalmus viridescens. This expression was verified by immunofluorescent staining using an Ab against axolotl C3 and by in situ hybridization with an axolotl C3 cDNA probe. In the early stages of regeneration C3 appeared to be equally present in all mesenchymal cells and in the wound epithelium, whereas in the later stages it was mainly expressed in the differentiating muscle cells. Since no expression was seen in the developing limb, it appears that the C3 expression was specific to the regeneration process. We then demonstrated by hybridization experiments that a blastema cell line of myogenic origin expresses C3. All these findings implicate C3 in the dedifferentiation process and may indicate a new role for this molecule in muscle differentiation.
Ambystoma↗
Complement (C3) receptor-mediated attachment of agarose beads to mouse peritoneal macrophages and human monocytes.
We have determined the receptors on human monocytes and mouse peritoneal macrophages producing agarose binding. By using isolated human complement factors C3, B and D, agarose beads were coated with C3b. In some experiments C3b was converted to C3bi by using human serum diluted 1:20. Agarose beads coated with C3b or C3bi bound strongly to monocytes. Only agarose beads coated with C3bi were attached to mouse macrophages. Trypsinization of agarose beads coated with C3bi abolished the attachment of the beads to macrophages and monocytes, probably because of conversion of C3bi to C3d. Endocytosis by macrophages of agarose preincubated in human serum or in C5-deficient AKR mouse serum reached the same levels, indicating that the amount of C5 present in serum during preincubation is not important for the degree of endocytosis. It is concluded that internalization of agarose by macrophages is mediated via the C3bi receptor.
Animals↗
Polymorphism of the third component of human complement (C3).
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Complement System Proteins↗
A simple procedure for isolation of Bufo arenarum C3 complement fraction and preparation of antiserum.
Because of the need for antibodies in our studies involving the third component of complement in Bufo arenarum, we performed a simple procedure to purify C3 from B. arenarum serum to use as antigen in the preparation of the antiserum. The strategy was based on the well-known ability of C3 to bind to zymosan (Zy), a yeast cell wall extract comprised of polysaccharides. The Zy-bound fraction showed cross reactivity with a commercial antibody to human C3 as well as a similar electrophoretic profile (SDS-PAGE) to C3 from other species. The Zy-C3 complex resulting from binding Zy to B. arenarum serum was injected into rabbits and the antiserum against this C3-like fraction was purified by protein A-Sepharose chromatography. The purified C3 antibody was found to be suitable for immunochemical studies.
Animals↗
Proteolytic activity of the different fragments of factor B on the third component of complement (C3). Involvement of the N-terminal domain of Bb in magnesium binding.
Kinetic experiments measuring the proteolytic activity of Bb and 33Kd fragment (the C-terminal domain of factor B) on C3 were performed in several conditions, in order to assess the role of factor B domains in the catalytic activity and magnesium binding. The experiments were carried out in fluid phase with 125I-C3 or C3(H2O) as substrates and in the presence of nonradioactive C3b as cofactor. The results indicate: (a) The C-terminal domain, 33Kd, possesses proteolytic activity on C3, which is Mg2(+)-independent, whereas proteolysis by Bb is enhanced in 5 mM Mg2+. (b) C3b behaves as cofactor of 33Kd proteolytic activity on C3 and factor H is able to inhibit this activity. (d) Kinetics of C3 proteolysis by 33Kd shows a lag phase which is also displayed by Bb in the absence but not in the presence of Mg2+. Taken together these data are consistent with the involvement of the N-terminal domain of Bb in Mg2+ binding, which results in an enhancement of the proteolytic activity on C3 of the adjacent C-terminal domain. A C3 convertase model accounting for these results is presented.
Complement C3↗
Kinetic studies on the fragmentation of the third component of complement (C3) by trypsin.
The kinetics of cleavage of C3 by trypsin was analyzed by electrophoresis in agarose and in polyacrylamide gels containing sodium dodecyl sulfate and the data obtained were used to construct an anatomical model for C3 showing the sites of tryptic attack, the fragments generated, and their composition. Trypsin was shown to cleave C3 in a stepwise fashion. The attack was initially directed at the alpha-polypeptide chain and resulted in the generation of C3a and C3b. Further cleavage of the alpha-chain of C3b, converted it into C3b1 and then into C3d and C3c. Cleavage of the beta-chain by trypsin occurred only at the C3c stage with the release of a small peptide (m.w. 12,000) from C3c and the formation of C3c'. On immunoelectrophoresis, C3c' had a less anodal mobility compared to the beta1A mobility of C3c. C3a, once formed could be further cleaved to give residual fragments with decreasing net positive charge. Exposure of C3 to acid conditions, pH 5.0 or below, rendered the molecule exceedingly susceptible to tryptic degradation.
Citrates↗
Interleukin-1 alpha enhances the biosynthesis of complement C3 and factor B by human kidney proximal tubular epithelial cells in vitro.
Local production in tubular cells of complement has been shown to occur in several kidney diseases by in situ hybridization, but the regulation at the local site during an inflammation is still unknown. In the present study, we demonstrate that human proximal tubular epithelial cells (PTEC) are able to produce complement components C3 and Factor B under non-stimulated conditions in vitro. The basal production of both was increased by 0.5 ng/ml interleukin-1 alpha (IL-1 alpha) for C3: from 95.5 +/- 4.0 ng/10(6) cells to 416.5 +/- 4.9 ng/10(6), and for Factor B: from 271 +/- 7.0 ng/10(6) cells to 457.5 +/- 7.0 ng/10(6) cells. In contrast cytokines such as TNF-alpha, IFN-gamma, IL-10 and IL-15 had no detectable effect. The upregulation by IL-1 alpha was dose- and time-dependent. The response to IL-1 alpha was shown to be mediated via the IL-1 receptor, as the addition of recombinant interleukin-1 receptor antagonist inhibited the IL-1 alpha induced complement production by more than 80%. IL-1 alpha enhanced mRNA expression of both C3 and Factor B as demonstrated by RT-PCR and dot-blot analysis. This indicated that IL-1 alpha upregulated the expression of the C3 and Factor B at the transcriptional level. We hypothesize that in vivo the production of C3 and Factor B at the local site during an inflammatory response in the kidney may be regulated by IL-1 alpha produced by inflammatory cells.
Cell Line↗
Cytotoxic and soluble mediator responses by complement (C3) receptor-bearing lymphocytes from patients with B-cell immunodeficiency diseases.
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Agammaglobulinemia↗
Complement C3 receptors: structure and function.
Significant progress has been made during the past few years toward elucidating the structure and function of various C3 receptors. Better understanding of the biochemical basis of the immune adherence phenomenon has been achieved. The availability of polyclonal and monoclonal antibodies to C3 receptors allowed more accurate studies of the cellular distribution of these receptors. Finally, advances in our knowledge of the functional properties of the C3 receptors and their relationship to specific cell surface molecules was facilitated by recognition of a patient deficient in various receptor-mediated functions. All together these developments will soon make it possible to describe in detail the molecular events involved in the modulation of complement receptor coupled cell functions.
Animals↗
Rapid onset monoclonal gammopathy in cutaneous lupus erythematosus: interference with complement C3 and C4 measurement.
Accurate nephelometric immunoassay requires both the analyte and the calibration standard to have the same molecular mass. Alteration in the size of the analyte can affect light scatter and yield erroneous results. We report a case where an autoantibody, a monoclonal IgM with immunoconglutinin activity, interfered with the nephelometric quantitation of plasma complement components C3 and C4.
Adult↗
Defective erythrocyte C3b receptor function associated with low serum complement (C3, C4) concentrations in insulin-dependent diabetes mellitus.
An immune adherence haemagglutination (IAHA) method was used to measure erythrocyte C3b receptor (EC3bR) activity in 110 patients with insulin-dependent diabetes mellitus (IDDM) and 223 controls. Results obtained from IDDM were correlated with serum complement concentrations (C3, C4) as well as with HLA types of the patients. We observed an increased frequency of defective EC3bR in IDDM (26.4%) compared to controls (10.8%, P less than 0.0005). Those patients who had defective EC3bR (IAHA negative) also had lower serum C3 and C4 concentrations than those with normal EC3bR function (IAHA positive). HLA-Dw3 positive patients had lower C4 concentrations than HLA-Dw3 negative patients and more often had defective EC3bR activity, although this difference was statistically not significant. Our results may indicate the close relationship between the risk factors which predispose to both IDDM and systemic lupus erythematosus.
Adolescent↗
[Subacute septicemia caused by Meningococcus of serogroup Y and acquired deficiency of complement C3 fraction].
The high frequency of meningococcal infections in patients with congenital deficiency of a component of the complement terminal pathway emphasizes the critical role of this system in host resistance against Neisseriaceae. We report the observation of a subacute septicaemia due to N. meningitidis serogroup Y. This girl had an acquired deficit of the C3 fraction of complement due to a high titre of C3 nephritic factor (C3NeF). There was no evidence of partial lipodystrophy or biological symptoms of glomerular disease. The meningococcal infection revealed this biological abnormality.
Child↗
The significance of serial measurements of serum complement C3 and C4 components and DNA binding capacity in patients with lupus nephritis.
Eighteen patients with systemic lupus erythematosus (SLE) and proliferative glomerulonephritis, underwent serial serum determinations of C3, C4, and native DNA binding capacity, as well as repeat renal biopsy 7 to 48 months (median 25 months) following initial biopsy. Highly significant correlations were found between serum C3 levels and renal histologic changes (P less than 0.0001), and between serum C3 levels and DNA binding capacity (P less than 0.03). Histologic deterioration correlated with depressed C3 levels, while improvement was associated with normalization of C3 levels. No correlation between renal histologic changes and either serum C4 levels or DNA binding capacity was found. The data suggest that the serum level of C3 is the best index of activity of lupus nephritis.
Adolescent↗
A complement C3 fragment equivalent to mammalian C3d from the common carp (Cyprinus carpio): generation in serum after activation of the alternative pathway and detection of its receptor on the lymphocyte surface.
A terminal degradation product (C3d) of mammalian complement component C3 plays an important role in modulation of the adaptive immune response through the interaction with complement receptor type 2 (CR2) on B cells. The present study is aimed at determining whether this is a functional bridge between the innate and adaptive immune systems in bony fish. The fragmentation of the complement component C3 in carp (Cyprinus carpio) serum, activated with zymosan, was analysed to ascertain if carp C3 also generates a mammalian C3d-like fragment under physiological conditions. A 35 kDa peptide reactive to the anti-carp C3 alpha-chain was detected on the zymosan particles and in the activated serum. Its N-terminal amino acid sequence identified it as carp C3d derived from the C3-H1 isoform. Another C3 isoform, C3-S, of carp was found to yield a C3d fragment at lower efficiency than C3-H1. Recombinant C3d fragments derived from C3-H1 and C3-S were produced in Escherichia coli as fusion proteins with glutathione-S-transferase (GST), and used for ligands to examine the presence of a possible CR2-like C3d receptor on carp lymphocytes. An enzyme-linked immunoadsorbent assay system, using the recombinant C3d proteins and anti-GST on a microplate to which was attached carp peripheral lymphocytes, detected a significant binding of carp C3d to the lymphocyte. The degree of binding of C3-H1-derived C3d was higher than that of C3-S-derived C3d. In addition, the binding of both ligands was inhibited by anti-C3 alpha-chain, but not by EDTA or EGTA, indicating that the putative C3d receptor does not require divalent cation. These properties agree well with those reported for mammalian CR2.
Amino Acid Sequence↗
Thyroid status influence on adiponectin, acylation stimulating protein (ASP) and complement C3 in hyperthyroid and hypothyroid subjects.
BACKGROUND: Thyroid abnormalities (hyperthyroid and hypothyroid) are accompanied by changes in intermediary metabolism including alterations in body weight, insulin resistance and lipid profile. The aims of this study were to examine plasma ASP, its precursor C3 and adiponectin in hyperthyroid and hypothyroid subjects as compared to controls. METHODS: A total of 99 subjects were recruited from endocrinology/out-patient clinics: 46 hyperthyroid subjects, 23 hypothyroid subjects and 30 control subjects. Subjects were evaluated for FT4, FT3, TSH, glucose, insulin, complete lipid profile and the adipokines: adiponectin, acylation stimulating protein (ASP) and complement C3. RESULTS: Hyperthyroidism was associated with a 95% increase in adiponectin (p = 0.0002), a 47% decrease in C3 (p < 0.0001), no change in ASP and increased ASP/C3 ratio (p = 0.0012). Hypothyroidism was associated with a 31% increase in ASP (p = 0.008). Adiponectin and C3 correlated with FT3 (r = 0.383, p = 0.004 and r = -0.277, p = 0.007, respectively) and FT4 (r = 0.464, p = 0.003 and r = -0.225, p = 0.03, respectively). ASP correlated with TSH (r = 0.202, p = 0.04). Adiponectin did not correlate with either ASP or C3, only ASP and C3 correlated (r = -0.197, p = 0.05). Adiponectin was negatively correlated with BMI, total cholesterol and plasma triglyceride, while C3 was positively correlated with BMI and total cholesterol. Surprisingly, adiponectin was positively correlated with insulin (r = 0.293, p = 0.02) and HOMA-IR (r = 0.373, p = 0.003) while C3 was negatively correlated with glucose (r = -0.242, p = 0.022, insulin (r = -0.184, p = 0.05) and HOMA-IR. CONCLUSION: These changes suggest that thyroid disease may be accompanied by changes in adipokines, which may contribute to the phenotype expressed.
Journal Article↗
Activation of complement C3 by different calcium phosphate powders.
The ability of different calcium phosphate to activate the complement system is studied by crossed immunoelectrophoresis demonstrating conversion of C3 to C3b. Complement consumption is determined by a haemolytic assay CH50. Hydroxyapatite powders after sintering induce a significant conversion of C3 and reduction of CH50 value. However the complement system is not activated by sintered tricalciumphosphate (beta-whitlockite). This is not related to the adsorption behaviour; it depends neither on chemical composition nor on crystal lattice. It is argued that C3 conversion is not triggered by the convertase of the classical pathway.
Calcium Phosphates↗
Cleavage of the third component of complement (C3) by mannose-binding protein-associated serine protease (MASP) with subsequent complement activation.
We have previously shown that a novel C1s-like serine protease termed MBP-associated serine protease (MASP) is responsible for activation of the complement cascade initiated by mannose-binding protein (MBP). In this communication, we report that MASP is unique in having the proteolytic capacity to cleave C3 with subsequent activation of the alternative pathway, a capacity which C1s lacks.
Carrier Proteins↗