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PubMedDate not supplied

In vitro activation of human complement by polyacrilonitrile dialyzer membrane assayed by complement binding to bystander red cells.

Quantitation of complement activation by polyacrilonitrile (PAN) dialyzer membrane is complicated by the high adsorptive capacity of the membrane for fluid phase anaphylotoxins. Assays for these anaphylotoxins, therefore, underestimate the degree of complement activation produced by this membrane. Alternative methods of measuring in vitro complement activation by the PAN and Cuprophan membranes were explored by incubating normal human erythrocytes with the membranes in the presence of serum. This led to deposition of C3d on these "innocent bystander" red cells, and provided an independent parameter for measuring complement activation. The PAN membrane caused significantly more C3d deposition on red cells, and thus more complement activation than Cuprophan. The possible significance of complement activation by PAN membrane, in consideration of its property of binding the resultant anaphylotoxins, is discussed.

Acrylic Resins↗
PubMedDate not supplied

Comparison of a quantitative microtiter method, a quantitative automated method, and the plate-count method for determining microbial complement resistance.

A quantitative microtiter method for determining the degree of complement resistance or sensitivity of microorganisms is described. The microtiter method is compared with a quantitative automated system and the standard plate-count technique. Data were accumulated from 30 avian Escherichia coli isolates incubated at 35 C with either chicken plasma or heat-inactivated chicken plasma. Analysis of data generated by the automated system and plate-count techniques resulted in a classification of the microorganisms into three groups: those sensitive to the action of complement; those of intermediate sensitivity to the action of complement; and those resistant to the action of complement. Although the three methods studied did not agree absolutely, there were statistically significant correlations among them.

Animals↗
PubMed1975

Complement components in normal serum and plasma quantitated by electroimmunoassay.

Sjöholm, A. G. Complement Components in Normal Serum and Plasma Quantitated by Electroimmunoassay. Scand. J. Immunol. 4, 25-30, 1975. The concentrations of C1q, C1s, C3, C4, C5, C3 proactivator, and C1 inactivator in serum and EDTA plasma from 100 normal adults were determined by electroimmunoassay. The normal range of each of the proteins is given. The C1q values varied more closely with the C1s values than with the levels of the other complement components. C3, C5, and C3 proactivator seemed to form a fairly interdependent group. The reproducibility of double determinations (interplate variation) was 4.9% to 7.9%. The variation of the complement component levels on repeated sampling from normal individuals was investigated. Also, repeated freezeing and thawing and storage at room temperature of serum and plasma were studied for their effect on the quantitation of the complement components. C3 and C4 values obtained by electroimmunoassay were in agreement with the values obtained by single radial immunodiffusion.

Adult↗
PubMed1992

Distribution and quantitative expression of the complement receptor type 1 (CR1) on human peripheral blood T lymphocytes.

The complement receptor, type 1 (CR1) is expressed on a variety of cell types including primate erythrocytes, phagocytic cells, and B lymphocytes. On these cells, CR1 plays a role in a diverse spectrum of biological activities including the clearance of immune complexes from the circulation, down-regulation of the complement system, recognition of complement-coated microorganisms, and cellular activation. CR1 is also expressed by some, but not all, T lymphocytes. The present study was undertaken in order to examine the distribution of CR1 on normal human T cell subsets by flow cytometry and to quantify the expression of T cell CR1 by radioimmunoassay. Data presented here indicate that, in a panel of 19 normal individuals, a mean of 9.7% of the overall peripheral blood lymphocyte population expressed CR1 and that, as assessed by two-color flow cytometry, 12.0% of CD3+, 13.0% of CD4+, and 20.0% of CD8+ cells expressed CR1. While single peaks of CR1 staining were observed within the CD3 and CD4 subsets, a biphasic pattern of staining was evident within the CD8 subset in which relatively high-intensity CR1 staining was detected within the subpopulation of "dull" CD8+ cells, whereas a lower intensity of CR1 staining was observed within the subpopulation of "bright" CD8+ cells. Duplicate analyses performed over a relatively short time frame suggested that, while the overall percentage of cells that expressed CR1 varied considerably among normal individuals, in at least some individuals the percentage of cells expressing CR1 was relatively stable, especially within the CD4 subset. In cell suspensions enriched for T lymphocytes by rosetting with sheep erythrocytes, 10.0% of the cells were CR1+ and a mean of approximately 3700 CR1 were expressed per CR1+ cell. There was no apparent correlation between the number of CR1 per T cell and the number of CR1 expressed per erythrocyte in the same blood sample. The expression of CR1 on subpopulations within the CD3+, CD4+, and CD8+ lymphocyte subsets may play a role in both normal cell function and in the pathophysiology of disease states including the acquired immune deficiency syndrome (AIDS).

Adult↗
PubMed1979

The quantitation of alternative pathway complement function by timed lysis assay.

A simple timed lysis assay is described for quantifying haemolytic complement activity in human serum. Classical pathway complement function was determined by measuring the time taken to lyse 50% of a standard suspension of antibody-coated sheep erythrocytes; the time required for 50% lysis of a standard rabbit erythrocyte suspension was similarly used to evaluate alternative pathway function. Because target erythrocytes prepared on different days gave slightly different 50% lysis times, it was necessary first to construct a series of calibration curves for converting 50% lysis times into CH50 U/ml. For this purpose, a range of dilutions of the standard human serum, of known haemolytic activity, was tested against erythrocytes prepared on 10 separate occasions. The standard serum was subsequently included with each batch of unknown sera and used to select the appropriate calibration curve for direct conversion of the 50% lysis time into CH50 U/ml. Eleven samples of normal human serum were tested by both the timed lysis assay and by the dilution methods of Mayer (1971) (classical) and Platts-Mills and Ishizaka (1974) (alternative pathway). Comparable results were obtained in all cases.

Animals↗
PubMed1977

Gingival fluid and serum in periodontal diseases. I. Quantitative study of immunoglobulins, complement components, and other plasma proteins.

1. Gingival fluid from severely inflamed periodontal tissue represents a 15 to 30% dilution of serum with respect to the proteins studied, with the exception of C3 and in some subjects, C4. 2. A marked decrease in C3 levels is found in most, if not all, gingival fluids, and a marked decrease of C4 levels is found in some gingival fluids. This suggests that complement might be activated during periodontal inflammation. 3. The concentrations of proteins in the gingival fluid are not related to their molecular weight.

Blood Proteins↗
PubMed1975

Factors affecting assay of myoglobin by complement fixation or immunodiffusion.

Quantitative micro-scale complement-fixation and semi-quantitative gel immunodiffusion assays for myoglobin have been evaluated experimentally and used to measure myoglobin in the sera of more than 1500 patients. We report certain problems, observations, and methodological improvements. Serum caused enhancement of precipitin lines in the immunodiffusion assay. In the complement-fixation assay, serum interfered both by enhancing or inhibiting complement fixation. Suggested modifications in the complement-fixation assay are: (a) routine threefold or greater dilution of serum with buffer and (b) use of serum-based rather than buffer-based calibration materials in preparing standard curves. Three cycles of freeze-thaw of serum or buffer decreased detectable myoglobin by 50-100%. We conclude that certain serum-related factors and freeze-thaw phenomena are important causes of error in immunological assays for myoglobin.

Complement Fixation Tests↗
PubMed1991

Use of heteropolymeric monoclonal antibodies to attach antigens to the C3b receptor of human erythrocytes: a potential therapeutic treatment.

We have prepared bispecific, cross-linked monoclonal antibodies (heteropolymers) with specificity for both targeted antigens and the human erythrocyte (RBC) complement receptor. These heteropolymers facilitate binding of target antigens (human IgG and dinitrophenylated bovine gamma globulin) to human RBCs under conditions that either allow or preclude complement activation. Quantitative analyses of this binding agree well with the number of complement receptors per RBC. In vitro "whole-blood" model experiments indicate heteropolymer-facilitated binding of antigens to RBCs is rapid and stable at 37 degrees C. It may be possible to extend these prototype experiments to the in vivo situation and use heteropolymer-attached RBCs for the safe and rapid binding, neutralization, and removal from the circulation of pathogenic antigens associated with infectious disease.

Antibodies, Monoclonal↗
PubMed1992

Properties of a low molecular weight complement component C6 found in human subjects with subtotal C6 deficiency.

A sensitive ELISA assay was used to quantitate serum complement component C6 concentrations. Levels in the range 0.3-3 micrograms/ml were measured in samples from eight individuals (four separate pedigrees) and two subjects with subtotal combined C6/C7 deficiency who have been reported previously. We defined C6 levels in this range as subtotal C6 deficiency (C6SD). In contrast, C6 deficiency with levels below 0.03 micrograms/ml was defined as C6Q0. C6Q0 has been found in 29 unrelated cases which have already been reported. Investigations of the properties of the C6 found in the C6SD subjects showed it to be haemolytically active and able to incorporate into the terminal complement complex. The protein had a relative molecular weight (Mr) of approximately 86% of normal C6 and this Mr was identical to that of the C6 of one combined deficient subject. The Mr of the C6 of the other combined deficient subject was previously estimated as 79% of the Mr of normal C6. Isoelectric focusing (IEF) analysis with band development by haemolytic overlay revealed that all C6SD samples produced an identical weak C6 band pattern anodal to normal C6A bands. The C7 IEF patterns of the two combined deficient subjects were identical, and the C6 IEF patterns of both were identical to those of the C6SD subjects. Thus the C6 of the combined deficient subjects is probably the same abnormal protein found in the C6SD individuals. None of the C6SD or combined deficient subjects have had meningococcal disease and it may be that low C6 levels afford some protection.

Adult↗
PubMed1976

Complement origin determines lytic activity of antibodies to nucleated target cells. Comparison of common complement sources.

The effects of complement from different species of animals were measured in a variety of antibody assays by using 51Cr-labelled target cells. Sheep antibodies were measured in samples of lymph and serum obtained from animals immunised with allogeneic lymphocytes, transplanted with allogeneic kidney grafts, or immunised with mouse tumour cells. Mouse (C57BL) antibodies were measured after immunisation with allogeneic tumour (P815) or after transplantation of allogeneic thyroid grafts (BALB/c). Different species of complement gave quantitative and sometimes qualitative differences when used to assay the same samples of antibody. In all systems tested, rabbit complement caused lysis of target cells at low antibody concentration when guinea pig and rat complements gave negative results, in some antibody-target cell combinations sheep complement was as effective as rabbit complement in mediating lysis. The different complement sources showed no selective lytic affinity for either IgM or IgG1 antibody subclasses purified from immune sheep lymph. Lysis of P815 target cells occurred more quickly when mediated by rabbit or sheep complement than when mediated by guinea pig or rat complement. Complement-dependent lysis sometimes occurred in systems where antibody, target cells and complement were obtained from the same species.

Animals↗
PubMed1978

Antibody-dependent cytotoxicity against Trypanosoma rhodesiense mediated through an alternative complement pathway.

A quantitative in vitro method was used to examine the role of classical and alternative pathways of complement activation in cytotoxicity against African trypanosomes by immune serum. This assay is based on the estimation of the extent of antibody-mediated cytotoxicity by measurement of inhibition of incorporation of [(3)H]leucine as an indicator of trypanosome metabolic integrity. To determine which pathway(s) is activated during cytotoxic events, complements sufficient in all components (C4S) and deficient in C4 (C4D) were used. Immune inhibition of [(3)H]leucine uptake by trypanosomes was observed in the presence of both complement sources. Treatment of C4S or C4D serum with cobra venom factor or disodium ethylenediaminetetraacetic acid abolished antibody-mediated cytotoxicity as well as immune hemolysis, thus suggesting the requirement for late-acting complement components. Ethyleneglycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid had no effect on inhibition of leucine incorporation, whereas immune hemolysis was inhibited, suggesting that cytotoxicity did not require C1 activation, a Ca(2+)-dependent event. The dependence of the cytotoxic process on Mg(2+) and not Ca(2+) ions and the fact that C4D guinea pig serum is fully active in trypanosome cytotoxicity indicate that an alternative pathway of complement activation is sufficient for activity.

Animals↗
PubMed1976

The alternate complement pathway in inflammatory bowel disease. Quantitation of the C3 proactivator (factor B) protein.

A component of the complement system's alternate pathway was investigated in ulcerative colitis and Crohn's disease. The mean C3PA (Factor B) titer in normals was 74 +/- 15%; in ulcerative colitis, 92 +/- 18%; and in Crohn's disease, 119+/- 24%. Significance was at the P less than 0.001 level when the mean values for the ulcerative colitis and the Crohn's disease groups were compared to normal subjects. Titers did not change significantly with exacerbation or amelioration of the diseases or when patient groups were analyzed according to the mode of treatment received.

Blood Proteins↗
PubMed1975

Effect of corticosteroids on the human monocyte IgG and complement receptors.

A quantitative in vitro assay was employed to directly assess the effect of corticosteroids on the IgG and complement receptor function of human mononuclear phagocytic cells. In this system corticosteroids were solubilized with cholesterol-phospholipid sonicated dispersions before exposure to mononuclear cells. Solubilized corticosteroids at concentrations between 10(-4) and 10(-3) M inhibited both IgG and complement receptor activity in a dose-response fashion. Inhibition was dependent upon the time of interaction of the mononuclear cells with corticosteroids and was half-maximal by 15 min. The inhibitory effect at all concentrations of hydrocortisone was partially overcome by increasing the number of IgG molecules per erythrocyte. Hydrocortisone also inhibited the binding of erythrocytes coated with both IgG and C3, despite the fact that when both were on the erythrocyte surface a synergistic effect on binding to mononuclear cells was observed. At the steroid concentrations employed, the capacity of mononuclear cells to exclude trypan blue and to take up latex particles and neutral red was unaffected. Mineralocorticoids also inhibited receptor activity, but the sex hormones were less effective. These studies demonstrate an effect of steroid hormones on cell membrane receptor function, and they suggest that an inhibition of the recognition system for IgG and C3 in vivo may explain, in part, the effect of corticosteroids in man.

Adrenal Cortex Hormones↗
PubMedDate not supplied

[The activation of the complement system in various connective tissue diseases].

A knowledge of the complement system in patients with collagen diseases is of interest as it may serve to indicate the existence of activity or non-activity in these diseases. We have studied the existence or non-existence of the activity of the complement system through evaluation of the levels of C3, as well as the implicated mechanism of the classical or alternate pathways through the measure of C'4 and C'3 proactivator components. Quantitation of complement components was obtained by electroimmunodiffusion, employing specific antiserum. From the results obtained, we observed that the complement activity in patients with SLE, the classic pathway was affected more (7 patients of the 24 studied), than the alternate pathway (3 patients). However, in those patients affected by sclerodermia, there seems to be an equal incidence of the activation of complement through both pathways (2 patients with activation through each way). Also of interest is the existence of a patient with SLE and another affected by sclerodermia in which a selective reduction of C'3 was observed. This observation suggests the possible existence of a selective destruction, perhaps mediated through a factor type such as the nephritic factor. However, there may exist other patients of whom we have already commented on, with a parallel reduction in the three components which suggests a change in the synthesis or in the simultaneous activation in both of the pathways. When realizing the comparative studies of the state in which the immunoglobulins (IgG, IgA and IgM) and complement components are to be found, the conclusion is that there is no significative correlation between the two. This is particularly interesting as it assumes the necessity of knowing the state of the complement and not only of the immunoglobulin, in order to know the state of activity in which the process is.

Complement C3↗
PubMed1979

Fluctuation of serum complement levels in children with neuroblastoma.

Serum samples from eleven children with neuroblastoma were drawn at diagnosis and again every 15 days or a month after the beginning of treatment over the course of 17 months observation. Twenty healthy children of the same age with no appreciable clinical manifestation were also studied as controls. Investigations included quantitative serum complement levels (total complement hemolytic activity, C3 and C4), anticomplementary serum activity and urine catecholamine levels (VMA and HVA). Complement levels of tumor patients were significantly higher than those of healthy subjects, but fluctuations were seen at different stages of the disease; patients at admission with active tumors or tumor recurrence had higher complement levels than those of patients in remission. Temporary recurrences of the disease were usually accompanied by fluctuations of urinary catecholamines, serum complement levels (mainly C3) and anticomplementary serum activity. At the terminal phase of the disease a drop in complement levels was usually seen, while urinary catecholamines were progressively increasing.

Bacterial Infections↗