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Results for “Complement C3d”

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PubMed1990

Concentrations of glycosaminoglycans in synovial fluids and their relation with immunological and inflammatory mediators in rheumatoid arthritis.

The dimethylmethylene blue assay showed higher concentrations of glycosaminoglycans in many synovial fluids from patients with rheumatoid arthritis (RA) than in autologous sera or sera or synovial fluids from normal subjects. These results were taken to suggest that the glycosaminoglycans in RA synovial fluid were abnormally raised and derived from cartilage. To discover what stimulated such glycosaminoglycan release in RA joints relations were sought between synovial fluid concentrations of glycosaminoglycans and immunological and inflammatory mediators. It was shown that RA synovial fluid glycosaminoglycan concentrations correlated with synovial fluid C3d concentrations but not with synovial fluid rheumatoid factor concentrations, polymorphonuclear leucocyte numbers, myeloperoxidase concentrations, or the ability of the synovial fluids to release free radicals from normal polymorphonuclear leucocytes. A correlation was found between synovial fluid C3d and interleukin 1 concentrations as judged by both lymphocyte activating factor activity and immunoassay, but no significant correlation was detected between interleukin 1 and glycosaminoglycan concentrations. It is suggested that in the rheumatoid joint locally produced cytokines, in addition to interleukin 1, together stimulate glycosaminoglycan release from cartilage and render it vulnerable to attack by other processes.

Adult↗

PubMed1992

Granulocyte elastase, beta-thromboglobulin, and C3d during acetate or bicarbonate hemodialysis with Hemophan compared to a cellulose acetate membrane.

Twenty-two patients were dialysed in a cross-over design using Hemophan or cellulose acetate membranes. The dialysate buffer was acetate (n = 12) or bicarbonate (n = 10). Blood was sampled at 0, 15, 60 and 180 min and mean values were adjusted for changes in total protein in each sample. At 15 min during dialysis a decrease in leukocytes and platelets occurred with both membranes, irrespective of the buffer (Wilcoxon, p less than 0.006). During dialysis, increases were found in granulocyte elastase inhibitor complex (E- alpha 1-PI), beta-thromboglobulin and C3d. beta 2-microglobulin was not significantly changed in blood after dialysis with Hemophan or cellulose acetate membranes with bicarbonate buffer. Side effects were more pronounced at 180 min during dialysis with bicarbonate in patients using cellulose acetate than with Hemophan (p = 0.021, n = 8). Hemophan seemed to be more favourable than cellulose acetate membranes in regard to leukopenia and E- alpha 1-PI. The dialysate buffer may also alter membrane biocompatibility.

Biocompatible Materials↗

PubMed1989

Storage of platelets in earth orbit. Effect of gravity and the formulation of plastic storage containers on platelet IgG and C3.

We investigated the effects of gravitational force and three different plastic formulations of the storage bags on the quality of stored platelets by measuring the changes in platelet-associated immunoglobulin G (IgG) and two antigenic markers of the third component of human complement (C3), C3d and C3c. Pooled platelets were stored in parallel at microgravity (MG) and on the ground (1 g) using three different plastic polymers: (1) polyvinylchloride (PVC) plasticized with di-2-ethylhexyl phthalate (DEHP); (2) PVC plasticized with trioctyl trimellitate (TOTM), and (3) unplasticized polyolefin (PO). The IgG and C3 were quantified by an automated antiglobulin consumption test in freeze/thaw disrupted platelets (total IgG or C3). The baseline values for platelet associated IgG and C3, measured after 2.5 days of storage at 1 g just prior to the launch, fell within the normal range. Following an additional 6.5 day storage, platelets stored at MG had accumulated significantly less C3d than those stored at 1 g, suggesting that MG storage was beneficial. Specific plastic formulations also exerted a significant effect on the accumulation of these immunoproteins, the effect being particularly pronounced at MG. The smallest increases of IgG and C3 were seen in platelets stored in TOTM and the largest in those stored in DEHP. It is possible that further studies at MG would permit a clear characterization of the effects of other independent storage variables.

Benzoates↗

PubMed2005

Immunogenicity of a bovine viral diarrhea virus E2-C3d fusion protein containing a bovine homolog of C3d.

Recently we demonstrated that attachment of three copies of murine C3d (muC3d) to the E2 envelope protein of bovine viral diarrhea virus results in a 10,000-fold increase in the immunogenicity of E2. Here we describe the cloning of the bovine homolog of C3d (boC3d), construction of an E2-boC3d expression cassette and expression and purification of the E2-boC3d fusion protein. We then show that E2, when coupled to boC3d, exhibits greatly enhanced immunogenicity. Thus, boC3d represents the second mammalian C3d homolog, thus far, shown to enhance the immunogenicity of a protein to which it has been coupled. Although the primary sequence of boC3d differs from muC3d by about 19%, we were able to demonstrate the enhanced immunogenicity of E2-boC3d using mice. The ability of boC3d to function in mice provides a less costly and more convenient animal model than cattle for the preliminary evaluation of E2-boC3d and other bovine antigen-boC3d fusion proteins.

Amino Acid Sequence↗

PubMed1989

The importance of C3d estimation in the diagnosis of generalized bacterial infections in newborn infants.

We evaluated the clinical relevance of a new C3d test in generalized bacterial neonatal infections. C3d was qualitatively evaluated by using an original counterimmunoelectrophoresis technique in 171 plasma. There were 13 cases of bacteriologically proven cases of septicemia and/or meningitis, 6 cases of probable and 42 cases of possible generalized infection. One hundred and ten non-infected samples were also tested. The sensitivity, specificity, positive and negative predictive values were 73.6, 83.6, 43.7 and 94.8%, respectively. The numbers of false positive and false negative were therefore found to be close to those observed when using classical infection markers.

Complement C3↗

PubMed1998

The mode of action of immunological adjuvants.

Adjuvants augment immune responses to antigens and influence the balance between cell-mediated and humoral responses, as well as the isotypes of antibodies formed. New adjuvant formulations include antigen-carrying vehicles and small molecules with immunomodulating activity. Widely used two-phase vehicles comprise liposomes and microfluidized squalene or squalane emulsions. These are believed to target antigens to antigen-presenting cells, including dendritic cells (DC), follicular dendritic cells (FDC) and B-lymphocytes. Activation of complement generates C3d, which binds CR2 (CD21) on FDC and B-lymphocytes, thereby stimulating the proliferation of the latter and the generation of B-memory. Targeting of antigens to DC may favour cell-mediated immunity. Immunomodulating agents induce the production of cytokine cascades. In a primary cascade at injection sites TNF-alpha, GM-CSF and IL-1 are produced. TNF-alpha promotes migration of DC to lymphoid tissues, while GM-CSF and IL-1 accelerate the maturation of DC into efficient antigen-presenting cells for T-lymphocytes. In a secondary cytokine cascade in draining lymph nodes, DC produce IL-12, which induces Th1 responses with the production of IFN-gamma. The cytokines elicit cell-mediated immune responses and the formation of antibodies of protective isotypes, such as IgG2a in the mouse and IgG1 in humans. Antibodies of these isotypes activate complement and collaborate with antibody-dependent effector cells in protective immune responses.

Adjuvants, Immunologic↗

PubMed2006

Hippocampal up-regulation of NCAM expression and polysialylation plays a key role on spatial memory.

Memory formation has been associated with structural and functional modifications of synapses. Cell adhesion molecules are prominent modulators of synaptic plasticity. Here, we investigated the involvement of the cell adhesion molecules, NCAM, its polysialylated state (PSA-NCAM) and L1 in spatial learning-induced synaptic remodeling and memory storage. A differential regulation of these adhesion molecules was found in the hippocampus of rats submitted to one training session in the spatial, but not cued, version of the Morris water maze. Twenty-four hours after training, synaptic expression of NCAM and PSA-NCAM was increased, whereas L1 appeared markedly decreased. The regulation of these molecules was spatial learning-specific, except for L1 reduction, which could be attributed to swimming under stressful conditions rather than to learning. Subsequent psychopharmacological experiments were performed to address the functional role of NCAM and PSA-NCAM in the formation of spatial memories. Rats received an intracerebroventricular injection of either a synthetic peptide (C3d) aimed to interfere with NCAM function, or endoneuraminidase, an enzyme that cleaves polysialic acid from NCAM. Both treatments affected acquisition of spatial information and lead to impaired spatial memory abilities, supporting a critical role of the observed learning-induced up-regulation of synaptic NCAM expression and polysialylation on spatial learning and memory. Therefore, our findings highlight NCAM as a learning-modulated molecule critically involved in the hippocampal remodeling processes underlying spatial memory formation.

Animals↗

PubMedDate not supplied

Complement binding to erythrocytes is associated with macrophage activation and reduced haemoglobin in Plasmodium falciparum malaria.

We have examined IgG and complement factor C3d deposition on erythrocytes by means of the direct Coombs' test (DAT) and looked for an association with the anaemia seen in falciparum malaria in children living in an area of hyperendemic malaria transmission (in Ghana). In one study (in 1997), 53 out of 199 patients had a positive DAT. Of these, 45 samples reacted with anti-C3d antibodies, 2 with anti-IgG and 6 with both reagents. There were significantly lower haemoglobin (Hb)-levels and higher prevalence of spleen enlargement in DAT-positive than in DAT-negative patients. Hb-levels were independently associated with DAT and age. This initial study was designed to investigate the role of intravascular haemolysis (IVH), but we found no association between IVH and either DAT result or anaemia. Because of the risk of selection bias we repeated the study using consecutive enrollment of malaria patients and were able to confirm the results in a total of 49 DAT-positive and 183 DAT-negative patients. This second study (in 1998) was designed to look at the importance of erythrophagocytosis through measurement of plasma neopterin levels and total nitrite and nitrate as markers of NO-release. Both parameters were significantly higher in DAT-positive than in DAT-negative patients (P < 0.001), indicating that complement binding to erythrocytes was associated with macrophage activation. Plasma levels of haptoglobin, interleukin-10 and tumour necrosis factor-alpha did not vary between the groups. The studies support the role of complement activation and erythrophagocytosis in the pathogenesis of anaemia in falciparum malaria in African children.

Analysis of Variance↗

PubMed1988

Comparison between a solid-phase low-ionic-strength solution antiglobulin test and conventional low-ionic-strength antiglobulin test: assessment for the screening of antierythrocyte antibodies.

A solid-phase low-ionic strength salt antiglobulin test (LISS-SPAT) has been developed using a microplate coated with dried sera as a solid phase. Before coating, the in vitro C3d fragment generation was activated by adding heat-aggregated immunoglobulin. The LISS-SPAT was compared with low-ionic strength conventional antiglobulin test (LISS-AGT) and also with a test using polybrene or papain microplates. When detecting the IgG and IgM antierythrocyte antibodies the reaction was developed in the same way in LISS-SPAT and LISS-AGT. In routine work, the LISS-SPAT provides a fast, reliable, handy and inexpensive screening of antibodies. This method appears to be an additional method to the papain and polybrene tests in microplates.

Blood Group Antigens↗

PubMed1989

Erythrocyte autoantibodies, autoimmune haemolysis, and myelodysplastic syndromes.

Immunohaematological investigations were carried out in 46 patients with erythrocyte autoantibodies associated with myelodysplastic syndromes. Eight patients had refractory anaemia, 17 refractory anaemia with ring sideroblasts, 11 refractory anaemia with excess of blasts, four chronic myelomonocytic leukaemia, five refractory anaemia with excess of blasts in transformation and one could not be classified. Standard agglutination direct antiglobulin tests showed that the red cells were most often coated with IgG and C3d, though increased amounts of IgM or IgA were also found in 15 of 35 cases (43%) when the more sensitive enzyme linked method was used. The IgG antibodies were predominantly of IgG1 subclass. Clinically important autoimmune haemolysis occurred in 15 patients, and was of "warm", "cold," and "mixed" types in seven, four, and four cases, respectively: it is important to recognise its presence in view of the good response to treatment. The increased incidence of erythrocyte autoantibodies in myelodysplastic syndromes is thought to be one manifestation of disturbed immune homeostasis.

Aged↗

PubMed1993

Erythrocyte autoantibodies, the monocyte monolayer assay and in vivo haemolysis.

Monocyte monolayer assays (MMA) were performed using red cells (RBCs) from 159 patients with a positive direct antiglobulin test and monocytes from healthy individuals. The results of the MMA reflected, to a great extent, in vivo haemolysis; 56/63 patients with a positive result, but only 10/96 with a negative one, had evidence of in vivo RBC destruction. Positive MMAs were observed with autoantibodies of all types: warm (42 cases), cold (14 cases), mixed (seven cases), but never in patients with only C3d on their RBCs and no detectable autoantibodies. With warm autoantibodies, the MMA results depended, in part, on the level of IgG sensitization; additional C3d coating acted synergistically to lower the amount of IgG necessary for monocyte interaction to occur. The presence of IgG3 as well as IgG1 on the RBCs was usually associated with a high MMA result; most of these cases, however, also exhibited larger amounts of cell-bound IgG. When the MMA results were analysed in respect of the various types of autoantibodies, differences in the phagocytosis:adherence ratio were observed; in patients with warm autoantibodies, there was a preponderance of phagocytosis, whereas in those with cold and mixed types, adherent RBCs predominated or were found alone.

Anemia, Hemolytic, Autoimmune↗

PubMed2001

Refractory hyperhaemolysis in a patient with beta-thalassaemia major.

We report the case of a 1-year-old girl with newly diagnosed beta-thalassaemia major. Following an initial blood transfusion with phenotypically matched blood, she developed a haemolytic anaemia which progressed with subsequent transfusions. The Direct Antiglobulin test (DAT) was strongly positive with C3d and weakly with IgG. The only free antibodies detected were a weak anti-H and a weak cold auto-antibody, which did not exhibit a wide thermal range. The indirect Donath-Landsteiner and Ham's tests were negative. There was no sustained clinical response to steroids, immunoglobulin infusions or splenectomy. An HLA identical sibling donor was available for allogeneic bone marrow transplantation (BMT) and the haemolysis resolved during the immunosuppressive transplant conditioning. Such hyperhaemolysis without significant red cell alloantibodies has previously been reported in patients with sickle cell anaemia, but only rarely in patients with beta-thalassaemia major.

Autoantibodies↗

PubMed2006

Decreased capacity of immune cells to cause tissue injury mediates kidney ischemic preconditioning.

Ischemic preconditioning (IP) is a well-established phenomenon, and the underlying mechanisms of IP are thought to involve adaptive changes within the injured tissue. Because one of the main functions of immune cells is to harbor memory, we hypothesized that circulating immune cells could mediate IP by responding to an initial ischemia reperfusion injury (IRI) and then mediate decreased injury after a second IRI event. C57BL/6 mice underwent 30 min of bilateral renal clamping or sham operation. At 5 days after ischemia, purified leukocytes from spleen were adoptively transferred into T cell-deficient (nu/nu) mice. After 1 wk, these mice underwent 30 min of renal IRI. The nu/nu mice receiving leukocytes from ischemic wild-type mice had significantly reduced renal injury compared with nu/nu mice receiving leukocytes from sham-operated, wild-type mice. Infiltration of neutrophil and macrophage in postischemic kidney did not correlate with the protection. No difference in kidney C3d or IgG deposition was detected between groups. Given that inducible NO synthase (iNOS) has been implicated in IP, leukocytes from ischemic or sham-operated, iNOS-deficient mice were transferred into nu/nu mice. Effects similar to those of wild-type transfer of ischemic leukocytes were demonstrated; thus, iNOS was not mediating the IP effect of leukocytes. This is the first evidence that immune cells are primed after renal IRI and thereby lose the capacity to cause kidney injury during a second episode of IRI. This finding may also be relevant for elucidating the mechanisms underlying cross-talk between injured kidney and distant organs.

Adoptive Transfer↗

PubMed1981

Neutrophil surface markers in patients with acute leukemia.

The presence of complement and Fc receptors on neutrophils from patients with acute leukemia was investigated at different stages of the leukemic process. Both Fc receptors (Fc-H and Fc-R) and one complement receptor (C3d) were normal when patients were studied at diagnosis, in relapse, and in remission. In contrast, the C3b receptor was significantly reduced on te neutrophils at the time of diagnosis, but returned to normal levels when patients entered remission. Variable amounts of C3b activity were observed in patients relapse, with approximately one-half of the patients showing decreased C3b activity. To determine whether the reduction inC3b receptors was specific for patients at diagnosis, three patients were studied at different times during their diseases. Normal receptor levels were detected in these patients during remission, but the C3b receptor was markedly reduced at diagnosis and at relapse.

Humans↗

PubMed1984

Polyclonal B cell activation, circulating immune complexes and autoimmunity in human american visceral leishmaniasis.

In a prospective study, serum and plasma samples from 17 patients with kala-azar were collected in Rio de Janeiro. High levels of immune complexes (IC) were detected in serum by means of 125I-Clq and conglutinin binding assays. The Clq binding material had a sedimentation coefficient of 19-25S, as determined by ultracentrifugation on sucrose gradient. Plasma levels of C3 and C3 breakdown products were measured and the C3d levels were increased in six out of 11 patients. The occurrence of polyclonal B cell activation was suggested by (a) a marked increase of serum IgG and IgM levels and (b) of the presence of antibodies against various proteins and haptens (SRBC, DNP-BSA, FITC-BSA,KLH). There was a close association between the presence of IC and anti-immunoglobulin antibodies. Anti-smooth muscle antibodies were also observed. These data are consistent with a major role of polyclonal B cell activation in the induction of IC during visceral leishmaniasis.

Adolescent↗

PubMed2006

Application of flow cytometry in detection of red-cell-bound IgG in Coombs-negative AIHA.

Coombs negative autoimmune hemolytic anemia (AIHA) is characterized by laboratory evidence of in vivo hemolysis along with a negative direct antiglobulin test (DAT) performed by conventional tube technique (CTT) in clinically suspected AIHA patients. The sensitive gel test (GT) and flow cytometry (FC) can effectively diagnose such patients where CTT does not detect low level of red cell autoantibodies. We investigated the use of FC in the serological evaluation of CTT DAT negative AIHA and its comparison with GT DAT. Of the 50 patients with suspected AIHA, CTT DAT was negative in 5 patients (Coombs negative AIHA). GT DAT could detect red cell autoantibodies in 4 of these 5 patients. Monospecific GT DAT showed IgG and/or C3d as the responsible autoantibody. FC was considered as reactive when MFI was >3.6 (mean of 20 healthy negative volunteers +2SD). FC was reactive in all five Coombs negative AIHA patients. The mean MFI in five known CTT DAT positive samples taken for comparison was significantly higher compared to 5 DAT negative AIHA (18.3 +/- 7.78 vs. 7.88 +/- 1.35, p < 0.05). There was poor correlation between strength of GT DAT and MFI by FC. We conclude that FC is more sensitive test than the CTT and helps in the serological diagnosis of Coombs negative AIHA. However, in resource poor settings, GT DAT can be a good alternative to FC.

Adolescent↗

PubMed1996

Sequence analysis of hypervariable region of hepatitis C virus (HCV) associated with immune complex in patients with chronic HCV infection.

Immune complex (IC) frequently exists in sera of patients with hepatitis C virus (HCV) infection. When circulating HCV particles are fractionated by differential flotation ultracentrifugation, HCV in the bottom fraction appears to be in the form of IC. Flotation ultracentrifugation of serum was done in 7 patients positive for serum anti-C3d-binding circulating IC and in 7 negative patients. In all IC-positive patients, HCV RNA was detected in the bottom fraction but not in the top fraction of 3 patients. Amino acid sequences of hypervariable region (HVR) of HCV in the bottom fraction of IC-positive patients were almost the same as those of whole serum, while those of the top fraction considerably differed from those of whole serum except for 1 case. These data suggest that the major population of HCV forms IC in IC-positive patients, and antibody response to the HVR of HCV is responsible for IC formation.

Aged↗

PubMed1985

Circulating Fc-receptor blocking factors in IgA nephropathies.

Twenty-one patients with primary IgA nephropathy, 7 patients with Henoch-Schönlein nephritis and 4 patients with IgA nephropathy associated to alcoholic liver cirrhosis were tested for Fc-receptor phagocyte function by measuring the clearance of radiolabelled IgG-sensitized erythrocytes in vivo and the immune phagocytosis by monocytes in vitro. Meanwhile IgG-, IgA-, IgA1-, IgA2-, containing immune complexes, the complement components C3, C4, C3d and the HLA-A, B, DR phenotype were determined. The patients with major urinary abnormalities were well discriminated from those with only minimal hematuria by a defective macrophage function (p less than 0.01) and high levels of IgA immune complexes (p less than 0.02). Since non HLA-A, B, C, DR phenotype was prevalent in patients who had defective Fc-receptor function, whereas a significant correlation was found between Fc-receptor impairment and levels of IgA immune complexes, it appears likely that circulating blocking factors, possibly related to IgA containing immune materials, may impair macrophage function in IgA nephropathies.

Adolescent↗