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At least 19 recordsLinked to original sources
PubMed1991

Effects of renal failure on complement C3d levels.

Elevated plasma concentrations of complement split product C3d have been reported to represent activation of the complement system. In the present study the effect of renal function on C3d concentrations was investigated in patients with various degrees of renal impairment, in patients with chronic renal failure and in CAPD patients. It appeared that elevated plasma C3d concentrations were present in patients with plasma creatinine concentrations in excess of 200 mumol/l regardless of the type of kidney disease. It is very likely that this can be attributed to renal handling (i.e. glomerular filtration, tubular reabsorption and renal catabolism) of C3d in a similar way as has been demonstrated for other low molecular weight proteins. The peritoneal permeability to C3d was slightly less than could be expected on the basis of its molecular weight without evidence of local production of C3d. Renal function should be taken into account in the interpretation of elevated plasma concentrations of C3d.

Complement Activation↗
PubMed1989

Changes in PMN leukocyte migration activity and complement C3d levels in RA patients with high disease activity during steroid treatment.

We have investigated chemotaxis of polymorphonuclear granulocytes (PMN) from 7 well characterized RA patients with intense disease activity, before and after steroid treatment. Increased spontaneous and directed granulocyte migration was observed in 6 out of 7 patients before steroid treatment. In 5 patients these parameters were reduced after treatment. In contrast to this, decreased chemotaxis of polymorphonuclear granulocytes (PMN) from patients with Rheumatoid Arthritis (RA), have been reported earlier. This has been suggested as a partial explanation of the increased morbidity of these patients. Plasma levels of Complement C3d were initially increased in all patients and were slightly reduced following treatment. PMN migration in highly active RA cases is increased and responds markedly to steroid treatment, in contrast to the complement activation. The mainly unaffected, increased levels of plasma C3d might, in part, explain the early recurrence of symptoms often seen when steroid medication is withdrawn. Our results contrast with earlier findings and need to be confirmed in further studies.

Acute Disease↗
PubMed1990

Specificities of monoclonal antibodies against the complement C3d split product.

The only specific method at present for the quantification of the complement split product C3d, the double-decker rocket immunoelectrophoretic assay, is work intensive and expensive. We investigated the possibilities for developing an ELISA for the direct quantification of C3d in plasma. Available antibodies were examined for their specificity for C3 and its degradation products by the PAGE immunoblotting method. None of the antibodies were specific for C3d, as cross-reactivities against C3 and/or C3b and C3bi were demonstrable.

Animals↗
PubMed1985

Identification and characterization of the Epstein-Barr virus receptor on human B lymphocytes and its relationship to the C3d complement receptor (CR2).

In pursuing studies on the early events in the infection of human B cells by Epstein-Barr virus (EBV), we examined the host cell attachment phase with a panel of B-cell-specific monoclonal antibodies. One of the monoclonal antibodies, OKB7, directly blocked the attachment of purified EBV to B lymphocytes in the absence of a second anti-immunoglobulin antibody and thereby prevented EBV infection of tonsil and peripheral blood B cells. Although earlier studies have shown a close association of the EBV and complement receptor (CR2), an anti-CR2 monoclonal antibody, anti-B2, did not directly block the binding of EBV to B cells. A comparison of the structures recognized by these monoclonal antibodies on various cell types and their functional and physiochemical properties was undertaken. Flow cytometric analysis revealed that the molecules detected by OKB7 and anti-B2 were coexpressed to the same extent on B cells but were not expressed on T-cell lines. OKB7 and anti-B2 both immunoprecipitated a 145,000-molecular-weight membrane protein with an isoelectric point of 8.2 from membrane extracts of Raji lymphoblastoid cells. OKB7 and, to a lesser extent, anti-B2 directly blocked the attachment of C3d,g-coated fluorescent microspheres and sheep erythrocytes bearing C3d to B cells, indicating that these antibodies also react with CR2. These studies indicate that the EBV-CR2 receptor is a single membrane glycoprotein which possesses multiple antigenic and functional epitopes.

Antibodies, Monoclonal↗
PubMedDate not supplied

Detection of complement (c3d) coated cells in a newborn due to maternal anti-i.

A case of a positive direct antiglobulin test on a newborn's cord red blood cells caused by maternal anti-i is reported. The direct antiglobulin test was moderately positive using polyspecific antiglobulin reagent and monospecific anti-C3d, but negative using monospecific anti-IgG. The infant showed no clinical signs of hemolytic disease of the newborn.

Blood Group Antigens↗
PubMed1988

Complement C3d,g/Epstein-Barr virus receptor density on human B-lymphocytes estimated by immunoenzymatic assay and immunocytochemistry.

The density of the C3d,g/Epstein-Barr virus receptor (CR2) on human mononuclear cells (MNC) isolated from CPD stabilized blood, was determined by comparing the concentration of CR2 antigen in extracts from Raji cells, with a known receptor density, with extracts of MNC. The concentration of CR2 was determined by a sandwich ELISA using two mutually non-inhibiting monoclonal anti CR2 antibodies (HB5 and OKB7). The percentage of CR2+ MNC was determined by an immunocytochemical staining method. Analysis of MNC from 20 healthy donors, revealed that the density of CR2 molecules varied from 3,600-7,700 on CR2+ cells, and that the percentage of CR2+ MNC had a mean of 13%.

B-Lymphocytes↗
PubMed1987

Identification of gp350 as the viral glycoprotein mediating attachment of Epstein-Barr virus (EBV) to the EBV/C3d receptor of B cells: sequence homology of gp350 and C3 complement fragment C3d.

The major Epstein-Barr virus (EBV) envelope glycoprotein, gp350, was purified from the B95-8 cell line and analyzed for its ability to mediate virus attachment to the isolated EBV/C3d receptor (CR2) of human B lymphocytes. Purified gp350 and EBV, but not cytomegalovirus, exhibited dose-dependent binding to purified CR2 in dot blot immunoassays. Binding was inhibited by certain monoclonal antibodies to CR2 and to gp350. Liposomes bearing incorporated gp350 bound to CR2-positive B-cell lines but not to CR2-negative lines. Liposome binding was also inhibited by the OKB7 anti-CR2 monoclonal antibody. A computer-generated comparison of the deduced gp350 amino acid sequence with that of the human C3d complement fragment revealed two regions of significant primary sequence homology, a finding which suggests that a common region on these two unrelated proteins may be involved in CR2 binding.

Amino Acid Sequence↗
PubMed1991

A flow cytometric assay for measuring complement receptor 1 (CR1) and the complement fragments C3d and C4d on erythrocytes.

A flow cytometric assay (FCA) was developed to measure complement receptor 1 (CR1) and the complement fragments C3d and C4d on erythrocytes. It was possible to measure these parameters accurately with intra- and interassay coefficients of variation of 2.0% and 6.5% respectively. The method was able to discriminate between low and high levels of erythrocyte CR1, C3d and C4d. Comparison with a previously described RIA method gave excellent correlation coefficients with r2 values of 0.94, 0.93 and 0.91 for CR1, C3d and C4d respectively. The flow cytometric assay was used to measure CR1, C3d and C4d on the erythrocytes of 98 healthy individuals and the 95% upper limits for C3d and C4d were established. There was a wide distribution of CR1 levels amongst these individuals but their C3d and C4d levels were low and often not above background. The possible application of this method in clinical medicine is discussed.

Antigens, CD↗
PubMed1990

Complement-activated oligodendroglia: a new pathogenic entity identified by immunostaining with antibodies to human complement proteins C3d and C4d.

Clusters of oligodendroglial fibers were identified immunohistochemically in human brain tissue with antibodies to the complement proteins C3d and C4d in several neurological disorders. These included Pick's, Huntington's, Parkinson's and Alzheimer's disease, amyotrophic lateral sclerosis, progressive supranuclear palsy and Shy-Drager syndrome. These complement-activated oligodendroglia occurred in selected areas of gray and white matter. They were rarely observed in control tissue. Immunogold electron microscopy established that the C4d antibody was attached to degenerating myelin sheaths. These data indicate attachment of classical complement pathway proteins to selective oligodendroglia in several neurological disorders.

Brain Diseases↗
PubMed1987

Assessment of complement activation during extracorporeal circulation by measurement of complement split C3d.

The present report summarizes our previous experience with the effect of various dialyzer membranes on leukocyte count, plasma C3d and C5a/C5ades-Arg, and total hemolytic complement. A relationship between the formation of C5a/C5ades-Arg within the dialyzer and hemodialysis leukopenia was demonstrated by comparing different membranes. Arterial plasma C3d was found to be a useful cumulative marker of complement activation during hemodialysis. C3d was shown to be generated in the artificial kidney with kinetics resembling the formation of C5a/C5ades-Arg. Total hemolytic complement transitorily decreased with all membranes, but did not reflect dialyzer biocompatibility. It is suggested that determination of complement-split C3d outdates previous more elaborate estimates of complement activation during hemodialysis.

Complement Activation↗
PubMed1987

The complement fragment C3d facilitates phagocytosis by monocytes.

Two receptors for fragments of C3 are described for human monocytes: CR1 and CR3, which bind C3b and iC3b, respectively. Recently a leucocyte receptor that binds C3dg has also been described, designated CR4. We previously reported that IgM-sensitized sheep erythrocytes that are heavily coated with C3d (EAC3d) can bind to human monocytes that have been cultured in fetal calf serum (FCS). Here we determine whether such binding of C3d-coated targets can lead to phagocytosis, and identify the specific monocyte receptor involved in C3d binding. We confirm that EAC3d bearing greater than 10,000 C3d/cell bind to FCS-cultured monocytes. Furthermore, using non-cultured monocytes, we demonstrate that C3d enhances rosette formation of IgG-coated E and, like C3b and iC3b, C3d augments IgG Fc receptor-mediated phagocytosis. Less than 100 C3d/cell are capable of enhancing phagocytosis, whereas 10,000 or more C3d/cell are required for rosette formation with cultured cells. These results indicate that the C3d-binding receptor is present on peripheral blood monocytes but has poor affinity for target particles coated only with C3d. Anti-CR2 monoclonal antibodies, which recognize the C3d receptor of lymphocytes, do not block EAC3d rosette formation with monocytes. In contrast anti-Mol, a monoclonal antibody against CR3, inhibits EAC3d rosettes by approximately 42%. Anti-CR1 increases this effect, but complete inhibition is not achieved. Ethylenediamine tetraacetate also markedly reduces EAC3d rosetting, reducing the numbers to less than 5%. Thus, the C3d-binding receptor on monocytes, unlike CR4, is metal dependent. Together these data indicate that CR3 is predominantly responsible for C3d binding to monocytes.

Antibodies, Monoclonal↗
PubMedDate not supplied

Detection of the complement (CD21)/Epstein-Barr virus receptor in human lacrimal gland and ocular surface epithelia.

CD21, the receptor for the C3d complement fragment, has been reported to be the Epstein-Barr virus (EBV) receptor in B lymphocytes and cultured squamous epithelial cells. This receptor has previously been found to be expressed in the epithelia of nonocular mucosal-associated lymphoid tissues (MALT) which are also sites of persistent EBV infection. We recently found evidence of persistent EBV infection in human ocular MALT and hypothesized that the epithelia in these tissues may also express the complement (C3d)/EBV receptor. To test this hypothesis, histologic sections of human lacrimal gland, ocular surface tissue (conjunctiva, limbus, and cornea), and conjunctival impression cytology specimens were stained by immunohistochemical techniques using three different anti-CD21 monoclonal antibodies (HB-5, B2, OKB7). HB-5 stained lacrimal gland ductal and all ocular surface epithelia, except limbus. B2 stained lacrimal gland ductal and limbal epithelia, and OKB7 stained only the limbal and corneal epithelia. The intensity of limbal and corneal epithelial staining with all anti-CD21 antibodies correlated with the level of epithelial differentiation, with the weakest staining noted in the cells which are thought to be the stem and transient amplifying cells of the cornea. These results suggest that external ocular tissues, similar to other MALT, have CD21-positive epithelia which may be potential targets for EBV infection.

Antibodies, Monoclonal↗
PubMed1987

Competitive enzyme-linked immunoassay for the quantitation of platelet-associated immunoglobulins (IgG, IgM, IgA) and complement (C3c, C3d) with polyclonal and monoclonal reagents.

A competitive enzyme-linked immunoassay (CELIA) was developed for the quantitation of platelet-associated immunoglobulins and complement proteins. The use of unlabeled polyclonal rabbit or monoclonal antibodies to human immunoglobulins and enzyme-labeled anti-mouse or anti--rabbit IgG (double-step technique) resulted in a higher sensitivity compared to the single-step technique using only enzyme-labeled anti-human immunoglobulin antibody preparations. Sensitivity and results obtained by both techniques were compared. The range of normal values for platelet-associated IgG, IgM, IgA, C3c and C3d was assessed upon a large number of normal blood donors. When platelet-associated IgG was concomitantly assayed with polyclonal and monoclonal anti-IgG by the double-step technique on platelets obtained from normal donors and thrombocytopenic patients, identical results were obtained with both reagents. Problems related to the quantitation of immunoglobulins on platelets with different assays and antibody preparations are discussed.

Antibodies, Monoclonal↗
PubMed1990

Reduction of complement activation during bypass by prime manipulation.

Complement activation is believed to be of importance in the development of complications arising after cardiopulmonary bypass. The effect on complement activation of priming the extracorporeal circuit with crystalloid alone, crystalloid plus albumin, or crystalloid plus the plasma expander polygeline was assessed in 36 patients undergoing coronary artery operations with cardiopulmonary bypass using a bubble oxygenator. Activation of the alternative and common complement pathways was monitored before, during, and after the bypass period by measuring concentrations of factor B and its fragment Ba and C3 and its fragment C3d. Complement activation occurred in all three groups of patients, with no difference between the crystalloid and crystalloid-albumin groups. In contrast, Ba fragment concentrations were persistently and significantly lower during and after bypass in the polygeline group, denoting reduced complement activation. C3d levels also showed a tendency to be lower in this group. Our results indicate that addition of polygeline to the priming solution reduces complement activation. Because complement activation is associated with morbidity after cardiopulmonary bypass, addition of polygeline to the priming solution may offer an inexpensive method of reducing morbidity after cardiopulmonary bypass.

Albumins↗
PubMed1990

Comparative study of assays detecting complement activation. Complement-split product C3d (rocket immuno-electrophoresis) and C3d neodeterminants (ELISA).

The aim of the study was to investigate the correlation between two types of assay measuring specific products of complement C3 activation and their clinical application. Complement C3d split product was estimated using double-decker rocket immunoelectrophoresis (DD-RIE) and measurements of C3d neodeterminants exposed after C3 activation was carried out with an enzyme-linked immunosorbent assay (ELISA). A total of 595 blood samples were measured in parallel in the DD-RIE and the ELISA test systems. The samples originated from blood donors (44), uraemic patients undergoing dialysis (135), serial samples from rheumatoid arthritis (RA) patients during steroid treatment (88) and 328 randomly collected patient samples. The mean values for DD-RIE and ELISA (+/- 1 SD) for the 595 samples were 48 (+/- 20) mU/l and 48 (+/- 28) mU/l respectively. The interassay coefficient of variation (CV) in the ELISA was 18%. The Spearman rho-correlation coefficient between the two assays was 0.63 for all 595 samples. The mean values using ELISA and DD-RIE were practically identical for the 328 successively incoming samples, the samples from the 135 dialysis patients and the 44 donors. In RA patients a higher mean value was found for the 88 samples using DD-RIE than ELISA. In the majority of patient samples there was a good correlation between the two assays. However, the ELISA appears to be more sensitive in detecting acute complement activation and to give lower levels in RA patients with chronic complement activation.

Anaphylaxis↗
PubMed1985

Mapping of the C3d receptor (CR2)-binding site and a neoantigenic site in the C3d domain of the third component of complement.

The C3d domain of C3 contains the site that binds to the C3d receptor (CR2) which is expressed on B lymphocytes. It also contains a neoantigenic determinant that is recognized by monoclonal antibody (mAb) 130 and is expressed when C3b is cleaved to iC3b and subsequently to C3dg or C3d. mAb 130 inhibits the binding of C3d to CR2. In this study, the locations of the CR2-binding site and of the neoantigen recognized by mAb 130 within the C3d domain were investigated. Treatment of human C3d with CNBr generated two major fragments with Mrs of 12,500 and 8600. Binding studies showed that only the Mr 8600 fragment was capable of binding to both CR2 and mAb 130. Amino-terminal sequence analysis of the Mr 8600 fragment and comparison with the amino acid sequence derived from human C3 cDNA [de Bruijn, M. H. L. & Fey, G. H. (1985) Proc. Natl. Acad. Sci. USA 82, 708-712] placed it between residues 1199 and 1274 of the C3 sequence. Several peptides were synthesized according to the derived C3 sequence of amino acid residues 1209-1236. Based on their differential binding to CR2 and mAb 130, we localized the CR2-binding site and mAb 130 neoantigenic site, respectively, to residues 1227-1232 and 1217-1232 of the C3 sequence.

Amino Acid Sequence↗