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PubMed2006

Serum concentrations of the third component of complement in healthy dogs and dogs with protein-losing nephropathy.

OBJECTIVE: To develop a method for determining the concentration of the third component of complement (C3) in canine serum, to establish a reference range for C3 in healthy dogs, and to evaluate dogs with protein-losing nephropathy (PLN) to determine whether PLN is associated with decreased serum C3 concentrations. ANIMALS: 30 healthy dogs and 49 dogs with PLN. PROCEDURES: Serum samples were obtained from healthy dogs at the time of examination, whereas serum samples were obtained from dogs with PLN at the time of diagnosis. All samples were frozen at -70 degrees C until analyzed. Serum C3 concentrations were determined by use of a sandwich ELISA. Concentrations were expressed as the number of dilutions in which C3 could be detected. RESULTS: C3 was detectable in healthy control dogs (range, 1,920,000 to 15,400,000 dilutions; median, 9,600,000 dilutions). This represented a range of four 2-fold serum dilutions. In addition, C3 was detectable in dogs with PLN (range, 1,460,000 to 30,070,000 dilutions; median, 7,680,000 dilutions), which represented a range of six 2-fold serum dilutions. There was no significant difference in C3 concentrations between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: C3 is a critical part of the immune defense system that has not been extensively examined in veterinary medicine. An ELISA was developed for measuring C3 concentrations, and a reference range for healthy dogs was established. Significant decreases in C3 concentrations were not detected in any dog with PLN. Additional studies will be required to definitively determine the importance of serum C3 concentrations in PLN.

Animals↗
PubMed1988

Analysis of the interaction between properdin and factor B, components of the alternative-pathway C3 convertase of complement.

The interactions between Factor B (B), its activation products Ba and Bb, properdin (P) and C3i or C3b, components that together form the alternative-pathway C3 convertase enzyme of human complement, have been analysed. Fluid-phase complexes of the purified components C3i, B and P were probed with the homobifunctional cross-linking reagent disuccinimidyl tartarate, and efficient cross-linking of B to P was observed. The 140 kDa B-P conjugate formed was cleaved by Factor D to yield a single product of 85 kDa. This is consistent with a Ba-P heterodimer, and suggests that the initial interaction of B and P includes an interaction of P with the Ba domain of intact B. (The Ba fragment is not retained in the active P-stabilized complex, C3bBbP). By contrast, no cross-linking of P to the Bb domain of B could be demonstrated. Binding studies on cellular intermediates also provided evidence for a site of interaction between B and P, with high concentrations of B inhibiting P binding to EAC3b (sheep erythrocytes coated with antibody and C3b). Neither isolated Ba nor Bb had any effect on the P-EAC3b interaction. High concentrations of B also accelerated the decay of the functional EAC3bBbP complex. These data indicate that the positive co-operativity of binding to C3i or to C3b between B and P is mediated, at least in part, through a direct interaction between B and P.

Complement Activating Enzymes↗
PubMed2003

Molecular characterization of the pig C3 gene and its association with complement activity.

The complement system catalyzes direct lysis of micro-organisms and modulates phagocytosis, inflammation, humoral and cellular immune responses. Since the complement protein C3 is the central component within all pathways of complement activation, C3 is a candidate gene for complement activity and also for improved protection against many pathogens. The pig C3 gene was sequenced, screened for polymorphisms, and analyzed for association with hemolytic complement activity of the alternative and classical pathway (AH(50), CH(50)). C3c serum levels and haptoglobin (HP) serum concentrations were measured before and after vaccination against Mycoplasma hyopneumoniae, Aujeszky virus, and porcine reproductive and respiratory syndrome virus in F2 animals of a pig resource population based on crossbreeding of Duroc and Berlin Miniature Pig. The genomic C3 sequence covers 444 bp of promoter region, 41 exons and 40 introns, as well as 881 bp of the 3'-flanking region. The cDNA codes for a 1,661-amino acid precursor C3. Five polymorphic sites were detected in the 5'-UTR, intron 13, exon 15, exon 30, and the 3'-UTR. Within the resource population two haplotypes were found to segregate. Analysis of variance applying a repeated measures model revealed a significant effect of the interaction of C3 genotype and time of measurement relative to immunization on CH(50), AH(50,)and C3c that is likely to be due to variation of C3 expression. In contrast, the time course of the HP acute-phase reaction is not associated with C3 genomic variation. The association of C3 with complement activity indicates the importance of C3 as a candidate gene for natural resistance to micro-organisms, although the causative polymorphism modulating the expression of C3 remains to be delineated.

Alleles↗
PubMed1981

Complement fixing properties of antibodies to double-stranded DNA in systemic lupus erythematosus.

Anti-DNA antibodies were assessed in 33 patients with active systemic lupus erythematosus (SLE) by the immunofluorescence Crithidia luciliae (CL) and the Farr assays. Eleven patients demonstrated complement (C3) fixation in the CL assay. Although 6 out of 9 patients with active nephritis showed complement fixation, 6 patients without overt renal disease were also positive in this assay. The ability to fix C3 was strongly associated with the total amount of anti-DNA antibodies as determined by both the CL and Farr assays (P less than 0.001). IgM anti-DNA antibodies were detected only in sera with complement fixing anti-DNA antibodies. Isolated whole IgG, but not the F(ab')2 fragment containing anti-DNA activity, fixed C3 on the Crithidia substrate. In depletion and reconstitution studies with human complement components, it was established that anti-DNA antibodies fixed C3 through the classical complement pathway although factors B and D of the alternative pathway were effective in C3 amplification. Properdin was also detected on the antigen-antibody complex but did not appear to be essential for maximal C3 fixation. Anti-DNA antibodies therefore fix complement by their Fc portion, form a classical pathway convertase, and recruit factors B and D of the C3b amplification loop when they bind to a fixed antigen.

Antibodies↗
PubMed1985

Immune defects in simian acquired immunodeficiency syndrome.

We recently reported a Simian Acquired Immunodeficiency Syndrome (SAIDS) in rhesus macaques at the California Primate Research Center. Here, we studied in vitro lymphocyte response to the mitogens Concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) with and without interleukin 2 (IL-2). Immunoglobulin (IgG and IgM) and complement (C3 and C4) concentrations were determined by radial immunodiffusion. T helper and T suppressor lymphocytes were identified with the monoclonal antibodies OKT4 and OKT8. Concentrations of IgG and IgM were significantly (p less than .05) decreased. Complement component C3 did not change but C4 was increased. The absolute lymphocyte count decreased but the OKT4:OKT8 ratio was unchanged from controls. A decreased lymphocyte response to all mitogens occurred early and became more severely depressed near death. IL-2 caused a complete or partial restoration of the response to the mitogens CON A and PHA. Both the humoral and cell mediated immune responses are affected in SAIDS. The role of IL-2 in this immune defect must be studied further.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Stimulation of complement production in mice by N alpha-(N-acetylmuramyl-L-alanyl-D-isoglutamine)-N epsilon-stearoyl-L-lysine.

N alpha-(N-acetylmuramyl-L-alanyl-D-isoglutamine)-N epsilon-stearoyl-L-lysine, a synthetic muramyl dipeptide analog, stimulated the production of the third component of complement (C3) in mice. The serum concentration of C3 was elevated significantly by subcutaneous treatment with a single dose (10 to 100 micrograms per mouse) of the adjuvant 24 h before assay of the serum. Thereafter, the concentration decreased gradually with time and returned to the normal level on day 4 to 5. Immunoelectrophoretic analysis of the serum revealed that the decrease in serum C3 could not be accounted for by the cleavage to C3a and C3b. By intermittent treatment with the adjuvant on every fifth day, a significant increase in serum C3 was repeated. However, no continuous retention of the serum level of C3 was established even during continuous treatment with the adjuvant once a day for 10 consecutive days. Instead, in this case, the level of C3 increased repeatedly at almost 5-day intervals.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMedDate not supplied

Quantitation of red cell-bound immunoglobulin and complement using enzyme-linked antiglobulin consumption assay.

Various techniques have been described for quantitating IgG or complement (C3) on red cells (RBCs). The techniques either are cumbersome, as the complement consumption test, or use radioactivity. This paper describes an antiglobulin consumption assay using an enzyme-linked immunosorbent method that can be used to quantitate IgG, IgM, and C3. With this technique RBCs from normal, healthy donors gave a mean value of 106 +/- 60 molecules of IgG per RBC, 4.5 +/- 3 molecules of IgM per RBC, and 37 +/- 28 molecules of C3 per RBC, respectively. The RBCs of hospital patients, particularly of those with infections or inflammatory conditions, contain increased amounts of nonspecifically bound immunoproteins. The availability of a common method to quantitate RBC-associated IgG, IgM, and C3 allows easy monitoring or study of the immune mechanism of autoimmune hemolytic anemia.

Adult↗
PubMed1982

Assessment of anti-stratum corneum antibody titres in pustulosis palmaris et plantaris.

Titres of anti-stratum corneum (SC) antibodies, determined by an indirect immunofluorescence (IF) technique, were significantly higher on average in pustulosis palmaris et plantaris (PPP) and pompholyx than in normal controls. By a complement IF technique, the antibodies fixed complement (C3) in high titer in PPP, but to a much lesser degree in pompholyx and normal controls. Direct IF microscopy studies showed the deposition of IgG and C3 in the SC in some of the biopsy specimens of the pustular lesions. These findings suggest that in PPP anti-SC antibodies may be involved at least in part in activation of the complement system and the subsequent accumulation of polymorphonuclear leukocytes.

Antibodies↗
PubMed1982

Activation of human complement by immunoglobulin G antigranulocyte antibody.

The ability of antigranulocyte antibody to fix the third component of complement (C3) to the granulocyte surface was investigated by an assay that quantitates the binding of monoclonal anti-C3 antibody to paraformaldehyde-fixed cells preincubated with Felty's syndrome serum in the presence of human complement. The sera from 7 of 13 patients with Felty's syndrome bound two to three times as much C3 to granulocytes as sera from patients with uncomplicated rheumatoid arthritis. The complement-activating ability of Felty's syndrome serum seemed to reside in the monomeric IgG-containing serum fraction. For those sera capable of activating complement, the amount of C3 fixed to granulocytes was proportional to the amount of granulocyte-binding IgG present in the serum. Thus, complement fixation appeared to be a consequence of the binding of antigranulocyte antibody to the cell surface. These studies suggest a role for complement-mediated injury in the pathophysiology of immune granulocytopenia, as has been demonstrated for immune hemolytic anemia and immune thrombocytopenia.

Arthritis, Rheumatoid↗
PubMed1977

Immunohistologic features of minimal-change nephrotic syndrome.

To assess the role of immune mechanisms in the pathogenesis of minimal-change nephrotic syndrome (MCNS), immunohistologic studies were performed on renal biopsy specimens from 31 patients. Glomerular immunoglobulin and/or complement (C3) deposition was present in 20 specimens. Deposits were usually minimal to moderate, granular, and focal in nature. IgM was present in 17 specimens, C3 in 10, IgG in 8 and IgA in only 3. With a mean follow-up of 5 1/2 years, there is no difference in the response to therapy of patients with no glomerular immunoglobulin or C3, those with glomerular immunoglobulin without C3, and those with glomerular C3. These findings indicate that glomerular immune deposits can be seen in a substantial percentage of patients with MCNS, but the minimal and focal nature of the deposits and lack of correlation with response to therapy suggest that immunoglobulin and C3 deposits are nonspecific and have no pathogenetic role.

Adolescent↗
PubMedDate not supplied

Antitumor effects of a new polysaccharide-protein complex (ATOM) prepared from Agaricus blazei (Iwade strain 101) "Himematsutake" and its mechanisms in tumor-bearing mice.

The antitumor activity of the i.p. or p.o. administration of polysaccharide-protein complex, ATOM (antitumor organic substance Mie) prepared from cultured mycelia of Agaricus blazei (Iwade strain 101) "Himematsutake" examined against four kinds of established mouse tumors. ATOM was highly effective at the doses of 10 and 20 mg/kg/day x 10 on subcutaneously implanted Sarcoma 180 in mice, and was also active against Ehrlich ascites carcinoma, Shionogi carcinoma 42 and Meth A fibrosarcoma at doses of 50 and 100 mg/kg/day x 10. ATOM has no direct cytotoxic action on tumor cells in vitro. Thus the tumor growth-inhibitory effect of ATOM is apparently due to immunological host-mediated mechanisms. The number of peritoneal macrophages, the phagocytosis of polystyrene latex beads and the proportion of the third component of complement (C3)-positive fluorescent cells were increased in the mice treated with ATOM. These results suggest that the macrophage activa-tion and alterations of the C3 are necessary for the induction of an antitumor effect of ATOM.

Animals↗
PubMed2001

Increased frequency of the C3*F allele and the Leiden mutation of coagulation factor V in patients with severe coronary heart disease who survived myocardial infarction.

The aim of the present study was to compare the frequencies of the F allele of C3 complement component and the Leiden mutation of coagulation factor V in patients with severe coronary heart disease (CHD) who survived myocardial infarction (MI; group A), and those who had no MI in their case history (group B). We have determined the C3 allele frequencies by electrophoresis, and Leiden mutation by PCR in 338 patients with severe CHD and in 490 and 523 healthy controls, respectively. The C3*F allele frequency was significantly (p = 0.006) higher in group A (0.213) that in group B (0.132). A significant (p = 0.045) difference was found between < or = 60-year group A (0.077) and group B (0.029) patients in the frequency of Leiden mutation. These findings indicate that the C3*F allele and the Leiden mutation may be associated with an increased risk of developing myocardial infarction in CHD patients.

Adult↗
PubMed1986

Dirofilaria immitis: diethylcarbamazine-induced anaphylactoid reactions in infected dogs.

The immunopathogenesis of the anaphylactoid Mazzotti reactions has been studied by comparing physiologic and immunologic aspects of diethylcarbamazine-induced shock in Dirofilaria immitis infected dogs with antigen induced anaphylaxis in infected and uninfected controls. Filarial antigen, specific host IgG antibody, and C1 and C3 complement levels were quantitatively measured over time in relation to the levels of histamine and prostaglandin D2 in the blood and changes in mean blood pressure. D. immitis antigen injected into uninfected dogs having no detectable IgG antibody to D. immitis or Toxocara canis produced a rapid drop in blood pressure that paralleled a drop in C1 and C3 levels and an increase in prostaglandin D2. Antigen injected into infected dogs with IgG antibody produced a similar drop in blood pressure and complement and increase in prostaglandin D2 which differed from the uninfected group only in the slower clearance of antigen from the blood. Diethylcarbamazine alone produced no measurable changes in blood pressure or complement in uninfected hosts. Diethylcarbamazine, however, administered into skin test positive infected dogs, produced a temporally slower but quantitatively similar loss in blood pressure, drop in complement, and increase in prostaglandin D2 and histamine to that induced by antigen injection. Complement activation and immune complex formation are initiated by antigen release, and subsequent vasoactive mediator release leads to shock with prostaglandin D2 being quantitatively higher in blood than is histamine.

Airway Resistance↗
PubMed2001

Systemic circulation of poly(L-lysine)/DNA vectors is influenced by polycation molecular weight and type of DNA: differential circulation in mice and rats and the implications for human gene therapy.

Effective gene therapy for diseases of the circulation requires vectors capable of systemic delivery. The molecular weight of poly(L-lysine) (pLL) has a significant effect on the circulation of pLL/DNA complexes in mice, with pLL(211)/DNA complexes displaying up to 20 times greater levels in the blood after 30 minutes compared with pLL(20)/DNA. It is shown that pLL(20)/DNA complexes fix mouse complement C3 in vitro, independent of immunoglobulin binding; are less soluble in the blood in vivo; bind erythrocytes; are rapidly removed by the liver, where they associate predominantly with Kupffer cells; and result in a rapid increase in hepatic leukocytes expressing high levels of complement receptor 3 (CR3). The circulation properties of these complexes are also dependent on the type of DNA used, with circular plasmid DNA complexes exhibiting increased circulation compared with linear DNA. PLL(211)/DNA complexes bind erythrocytes and associate with Kupffer cells but, in contrast, do not fix mouse complement in vitro and are unaffected by the type of DNA used. In rats, both types of complexes produce hematuria and are rapidly removed from the circulation. Correlation of in vivo and in vitro results suggests that the solubility of complexes in physiological saline and species-matched complement fixation and erythrocyte lysis may correlate with systemic circulation. Analysis using human blood in vitro shows no hemolysis, but both types of complexes fix complement and bind IgG, suggesting that pLL/DNA complexes may be rapidly cleared from the human circulation.

Animals↗
PubMed1987

Diamide enhances phagocytosis of human red cells in a complement- and anti band 3 antibody-dependent process.

Human red cells treated with 20-200 microM diamide were opsonized by serum and phagocytized by adherent monocytes. Phagocytosis was dependent on complement. It was enhanced by supplementing whole serum and was restored by supplementing complement-inactivated serum with naturally occurring antibodies which bind to the major integral protein of the human red cell, band 3 protein. Diamide induced oligomers of anti band 3 reactive oligomers, and enhanced anti band 3 binding to red cells. Complement C3 binding paralleled that of anti band 3 and exceeded it by two orders of magnitude. Thus, naturally occurring antibodies have functional properties which were not abolished by other serum Ig and may be involved together with complement in the clearance of red cells subjected to oxidant stress.

Anion Exchange Protein 1, Erythrocyte↗
PubMed2004

C-reactive protein accelerates the progression of atherosclerosis in apolipoprotein E-deficient mice.

BACKGROUND: Plasma C-reactive protein (CRP) concentration is a strong predictor of atherosclerosis. However, to date, there is no in vivo evidence that CRP is proatherogenic. METHODS AND RESULTS: We studied the effect of human CRP transgene (tg) expression, under basal and turpentine-stimulated conditions, on atherosclerosis in apolipoprotein (apo) E-/- mice. Aortic atherosclerotic lesions in 29-week-old male mice were 48% larger (P<0.02) in turpentine-treated mice and 34% larger (P<0.05) in untreated CRPtg+/0/apoE-/- mice. Turpentine treatment per se did not affect the extent of atherosclerosis in CRP transgenic or nontransgenic apoE-/- mice. Transgenic mice exhibited lower plasma complement C3 but increased deposition of CRP and C3 in the lesions, which suggests that CRP stimulated activation of complement within the lesion. There was more intense and widespread vascular cell adhesion molecule-1 and collagen staining in the lesions of CRPtg+/0/apoE-/- mice than in CRPtg0/0/apoE-/- littermates. Lesions of CRPtg+/0/apoE-/- mice contained increased angiotensin type 1 receptor (AT1-R) transcripts and displayed increased AT1-R immunostaining compared with those of CRPtg0/0/apoE-/- mice. There was no difference in blood pressure in the 2 types of mice, which indicates that the proatherogenic effect of CRP-associated AT1-R overexpression is local and not mediated by its hypertensive properties. CONCLUSIONS: Human CRP transgene expression causes accelerated aortic atherosclerosis in apoE-/- mice. CRP was detected in the lesion, which was associated with increased C3 deposition and increased AT1-R, vascular cell adhesion molecule-1, and collagen expression. These data document a proatherogenic role for CRP in vivo.

Animals↗
PubMed1983

Crossed immunoelectrophoresis for the detection of split products of the third complement in dengue hemorrhagic fever. I. Observations in patients' plasma.

Crossed immunoelectrophoresis was applied to detect the products of the third component of complement (C3) activation in plasma of patients suffering from dengue hemorrhagic fever (DHF), using inulin-treated normal human sera as positive control. In DHF, C3 split products were demonstrated in severely ill patients classified as having Grade III and Grade IV disease. These split products rapidly disappeared during the convalescent phase. The appearance of C3 activation products in DHF correlated well with signs of shock. This electropherogram of C3 activation could be used as a parameter reflecting immunologic activity in dengue hemorrhagic fever.

Adolescent↗