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PubMed1976

Symptoms and immunology of the Henoch-Schönlein-syndrome.

The Henoch-Schönlein-syndrome, or anaphylactoid purpura, is usually a childhood disease. The progess of this syndrome in adults was observed in 4 cases at our clinic. An elevated IgA level in the serum with a normal complement value seems to be of immunological interest. By immunohistological methods fibrin and IgA could be demonstrated in skin and kidney biopsies; in glomerulae C3c was observed, occasionally accompanied by Properdin-factor-B. These findings differentiate this disease from other allergic superficial vasculitids by the detection of IgG and complement; while at the same time some similarities are indicated to the so called "Berger Nephritis" with comparable kidney findings.

Adult↗

PubMedDate not supplied

Quantitative determinations of immunoglobulins and complement components in human aortic atherosclerotic wall.

Saline and acid eluates of intima with only fatty streaks, fibrous plaque and intima surrounding the fibrous plaque were obtained from 42 human aortae. IgG, IgA, IgM, C1q, C3c, C4, C9, C3A, C-reactive protein, alpha-1-antitrypsin, alpha-2-macroglobulin, albumin, transferrin and fibrinogen were quantitatively determined in these eluates using the radial immunodiffusion technique. Saline extracted IgG and IgA were significantly higher in the fibrous plaque and adjacent tissue than in the fatty streak intima, where IgM was the highest. IgG and IgA were only present in acid eluates. The complement components were present in all saline eluates, but only traces of C3c and C1q in some acid eluates. Statistically significant differences were found for C1q and C9. C-reactive protein was present in 23 samples. The results could suggest an involvement of immune mechanisms in the progression of the atherosclerotic lesion.

Adolescent↗

PubMed1984

Schistosoma mansoni: escape from complement-mediated parasiticidal mechanisms following percutaneous primary infection.

Schistosomula were recovered from the skin of mice following primary infections. On the surface of such "infecting schistosomula", mouse C3 could not be detected by immunofluorescence. Subsequent incubation in vitro with fresh mouse serum led to the effective deposition of mouse C3 on schistosomula only when they were recovered within a few hours but not after one or two days following infection. In vitro deposited murine C3c was lost from i.v. injected schistosomula in the mouse circulation within one day as was human C3c. Infecting schistosomula exhibited a close to complete resistance to the lytic in vitro activity of human complement. This resistance was complete in older parasites. It existed in spite of the presence of parasite-bound human C9, which was detectable on all developmental stages of schistosomes following incubation in fresh, but not inactivated human serum. Lung schistosomula, 3-week and 6-week-old schistosomes were resistant to cellular cytotoxicity upon incubation with fresh human serum and rat peritoneal exudate cells although cell adherence mediated by human C3b was demonstrated with lung worms. The data suggest that schistosomula may evade in vivo the lytic activity of complement and also complement-mediated cellular cytotoxicity. Depending on the species of serum, this can be demonstrated in vitro by lack of opsonization or by resistance to lytic and cellular attack mechanisms.

Animals↗

PubMed1982

An example of a naturally occurring anti-cE (Rh27) that binds complement.

A serum sample from a nontransfused male containing anti-Rh27 and an additional weakly reacting antibody was investigated. One absorption of the serum with RZR1 cells left only anti-Rh27 while repeated absorption with R1R1 cells or autologous cells had no effect. Treatment of the serum with reducing agents destroyed all activity suggesting the antibody was predominantly IgM. Tests with monospecific antiglobulin reagents in the indirect antiglobulin test revealed very weak reactions with anti-IgM and anti-IgA, no reactions with anti-IgG, and strong reactions with anti-C3(C3c + C3d) and anti-C4. This is the first reported example of a naturally occurring complement binding anti-Rh27.

Absorption↗

PubMed1988

Enhancing effect of autologous human erythrocytes on generation of C3 cleavage products beyond iC3b.

The in vitro formation of C3d and C3c in fresh normal human serum (NHS) after addition of five different activators of the complement (C) system was studied. Following C-activation in NHS (n = 53) by Sephadex G-200 beads, the conversion of C3 was found to proceed to iC3b with a variable but restricted generation of C3d. Similar results were obtained by use of heat-aggregated IgG, Escherichia coli, zymosan, and cobra venom factor. However, comparing the C3d concentration following activation in the presence and absence of autologous red blood cells (RBC) at 37 degrees C the generated C3d was found to be 2- to 3-fold higher in the presence of RBC after 30, 60, and 210 min. Preincubation of RBC with polyclonal anti-CR1 antibodies resulted in a dose-dependent reduction of the amount of C3d generated. C-activation induced by Sephadex G-200 beads, in the absence of RBC, generated iC3b without a significant production of C3d. After removal of the activator beads, addition of RBC resulted in a decrease of iC3b and a clear increase in the C3c and C3d concentration within 3 h. Western blotting analysis of the C3d produced in the presence of RBC showed that the molecular weight (36 kilodaltons) was similar to that of C3d formed in vivo.

Blotting, Western↗

PubMed1994

Erythrocytes from young but not elderly donors can bind and degrade immune complex- and antibody-bound C3 in vitro.

In situ aged erythrocytes (senescent erythrocytes from young donors and both young and old erythrocytes from elderly donors) demonstrate high levels of membrane-bound C3c and C3d and elevated susceptibility to in vitro phagocytosis. In this study we demonstrate that in situ aged erythrocytes are defective in their ability to degrade C3 fragments and clear them from the erythrocyte membrane. Erythrocytes from young donors bind complement-bearing immune complexes via CR1 and become susceptible to complement-mediated erythrophagocytosis ('innocent bystander' sequestration). Erythrocytes from elderly donors are defective in their ability to bind such immune complexes, as attested by the lack of an increment in membrane-associated C3 fragments as detected by flow cytometry and lack of an increment in in vitro sequestration. Factor I (serum)-dependent cleavage of C3 fragments and release of immune complexes from the erythrocytes of young donors lead to a drop in erythrocyte-associated C3 fragments and the disappearance of the 'innocent bystander' phenomenon. Inhibition of Factor I, and thus inhibition of C3b degradation and immune complex release for the erythrocyte membrane, enhances the levels of 'innocent bystander' sequestration of erythrocytes from young donors. Erythrocytes from elderly donors are defective in the dynamic process of CR1 binding of complement-bearing immune complexes and Factor I-associated release of membrane-associated C3 fragments. A defect in the ability of all in situ aged erythrocytes to clear their membranes of C3 fragments is also demonstrated for complement bound to the erythrocyte via IgM isoagglutinins. While erythrocytes from both young and elderly donors allow for the IgM-mediated binding of complement to the erythrocyte, only young erythrocytes from young donors demonstrate degradative activity with the release of membrane-associated C3c. Erythrocytes from elderly donors demonstrate lower levels of detectable CR1 (CD35), decay accelerating factor (DAF) (CD55) and Protectin (CD59) than do erythrocytes from young donors. Time course studies determine that the defect in handling of immune complexes observed for in situ aged erythrocytes is not due to differences in the kinetics of loading or releasing of immune complexes. These findings on the refractiveness of erythrocytes of elderly donors to uptake of immune complexes and the degradation of C3 fragments may be of importance not only in the understanding of erythrocyte sequestration, but also in the physiology of immune clearance in the elderly.

Adolescent↗

PubMed1989

A new method for the estimation of C3d. Affinity clearance of C-determinant-bearing C3 molecules and fragments followed by estimation of C3d by ELISA.

A method is described to quantitate human complement fragment C3d. Test samples were treated with a predetermined excess of anti-C3c-Sepharose beads in the presence of EDTA to remove all the C-determinant-bearing C3 molecules or fragments. C3d left in the supernatant was then estimated by ELISA. Using this method, C3d could be estimated accurately in normal plasma samples. A good correlation (r = 0.93) was observed between C3d values obtained by this method and values obtained by the widely used method of Perrin and coworkers. The average C3d plasma concentration was 2.8 mg/l (SD = 0.7 mg/l, n = 21). The interassay coefficient of variation using a normal plasma pool (C3d 2.7 mg/l) was 8.3% and using normal plasma pools in which the C3d concentrations were raised to 10.3 and 17.4 mg/l by the addition of aged normal serum the levels were 8.0 and 7.5% respectively. Intra-assay coefficients of variation with these samples were 4.6, 3.0 and 2.8%, respectively. 16 patients with renal dysfunction had C3d levels in the range of 4.3-10.0 mg/l and 15 patients undergoing continued ambulant peritoneal dialysis had levels of 3.3-12.2 mg/l. The C3d content in peritoneal dialysate of patients undergoing dialysis varied from 9.3 to 383 micrograms/l.

Antibody Specificity↗

PubMed1976

Detection of complement activation by counterimmunoelectrophoresis (CIE).

Counterimmunoelectrophoresis (CIE) was used as a method of detecting activation of the third component of the complement system (C3). Highly purified C3, normal human serum (NHS), EDTA-treated plasma and serum activated with aggregated human immunoglobulin (agg-IgG) or inulin were used as sources of C3 and/or C3 split products. Activation of the alternative pathway of complement was assayed in the presence of EGTA (10 mM) and MgCl2 (0.3 mM), conditions which block activation of the classical pathway. When purified native C3, fresh NHS and fresh EDTA-plasma were tested in CIE against either antisera to whole C3 or to C3 split products, only one precipitin line was found, which was identified as native C3. However, when serum activated with agg-IgG or inulin were tested against the same reagents, two precipitin lines were seen. The first, with more cathodal mobility was identical to that of native C3. The second line had a more anodal mobility, was distinctly separated from the first and contained C3c and C3d as shown immunochemically with specific antisera. Native C3 and split products of C3 were identified by this CIE method in patients showing evidence of activated complement by having subnormal total complement (CH50) levels. When C3 split products were identified, the C3c-C3d precipitin line could always be distinguished from native C3 by its different electrophoretic mobility, even when C3 concentrations in serum varied from 0.25 mg/ml to 1.5 mg/ml. The sensitivity of CIE was compared to that of CH50 by asssaying at different time intervals after agg-IgG was added to fresh NHS. C3c-C3d split products were detected by CIE before any fall in CH50 and at all times when a significant decrease in CH50 was present. This study shows that the CIE technique is a highly sensitive, specific and rapid method for detecting activation of the complement system via classical or alternative pathways in human disease.

Complement C3↗

PubMed1990

S protein binds to serum-treated agarose beads independently of complement activation and the formation of the terminal complement complex on the beads.

Comparison of initial (early-phase) and terminal (late-phase) sequence activation of complement by agarose beads and endotoxin was evaluated in an enzyme immunoassay (EIA) of serum levels of C3c and C9 neoepitopes, respectively. EIA and Western blotting with anti-S protein monoclonal antibody revealed lower S protein values and weaker S protein bands in serum activated by agarose beads than by endotoxin, implying that S protein was removed from serum by binding to agarose. The binding of S protein to the beads was confirmed by radioimmunoassay and was found to be equal in normal and heat-inactivated serum. In contrast, the terminal complement complex was formed only on agarose beads incubated with normal serum and not with inactivated serum.

Blood Proteins↗

PubMedDate not supplied

Immunoglobulins and complement components levels in patients with lung cancer.

Sera from 96 patients with lung cancer were assayed in order to evaluate the concentrations of IgG, IgA, IgM, C3c and C4. Histologically, 49 of the patients had squamous cell carcinoma, 11--adenocarcinoma, 20--small cell carcinoma and 16--not identified lung cancer. No statistically significant differences were found between the concentrations of IgG and IgM in patients with carcinoma of the lung versus subjects in the control group. Both serum IgA and complement components (C30 and C4) were significantly elevated in almost all patients from the tumor group as compared with the levels in the control group.

Adenocarcinoma↗

PubMed1985

Activation of the alternative complement pathway in normal human serum by Loa loa and Brugia malayi infective stage larvae.

Infective stage larvae (L3) of Loa loa and Brugia malayi upon in vitro incubation with normal human serum activated the alternative complement pathway. C3 conversion products were detected on larval cuticles by eosinophil adherence and by immunofluorescence with C3c antiserum. No evidence for cuticle binding of IgG, IgA, IgM, Clq, or C4 was found by immunofluorescence. L3-induced C3 activation was inhibited by 10 mM EDTA but unaffected by 10 mM Mg++-EGTA. Human sera deficient in C2, C4, or C6 incubated with L3 resulted in C3 activation. However, sera treated with zymosan or heated for 1 h, 56 degrees C were unreactive with L3. Immunoelectrophoresis of fresh serum exposed to L3 for 1 h at 37 degrees C showed C3 cleavage products. The results indicate that these nematode L3 activate the alternative complement cascade via cuticular surface components. Larval viability was unaffected by complement activation or by adherence of eosinophils.

Animals↗

PubMed1977

Comparison of low-molecular-weight products following reaction of C3-C3b with C3b inactivator and with trypsin.

Substitution of trypsin for Konglutinogen-activating factor (KAF) in the procedure for cleaving C3d from C3-C3b substrate produced a relatively heterogeneous low-molecular-weight fraction (C3d-Tryp) which differed in a number of ways from the KAF-mediated cleavage product (C3d-KAF). The differences were demonstrable by agar and polyacrylamide gel electrophoresis, 125I-labelling, content of immunoreactive 125I-labelled C3d, inhibition of anti-complement antiglobulin reagents and rabbit immunization. By comparison with C3d-KAF, the C3d in C3d-Tryp was more heterogeneous and exhibited a faster electrophoretic mobility in agar at pH 8.6. By contrast to C3d-KAF, C3d-Tryp contained protein carrying C3c antigenic determinants.

Complement C3↗

PubMed1993

Evaluation of complement activity by an enzyme immunoassay.

An ELISA-type assay useful for the evaluation of the complement activity in serum is described. Aggregated pooled human IgG (IgGn) prepared so as to exclude large and small aggregates, to resemble soluble circulating immune complexes, was used to coat polystyrene microwells to serve as initiator of complement activation. Fresh serum, at different dilutions, as the source of the complement to be evaluated was added and the plate incubated 90 min at 37 degrees C. Then, a peroxidase-labeled antihuman C3c antibody was added to react with the bound C fragments. This was followed by 2,2'-azino-di-3-ethyl benzothiazoline sulfonic acid (ABTS), as the color reagent used for detection of the enzyme activity. In this system, theoretically, the levels of activating and regulatory complement components are evaluated up to the level of C3 splitting. The assay was applied in healthy volunteers to set normal values and in 15 patients suffering from systemic lupus erythematosus making possible the differentiation of those with normal and low complement levels.

Complement Activation↗

PubMed1979

C3d antiglobulin haemagglutination of human red blood cells. A demonstration of two types of cell-bound C3d by means of typsin digestion.

Washed human red blood cells from blood collected in EDTA were tested by Auto-Analyzer for a percentage of maximum antiglobulin haemagglutination (AH) using monospecific antisera to human C3d and C3c. The cells from normal persons were found to be agglutinated by anti-C3d but not by anti-C3c. To a fixed dilution of antiserum, the normal C3d AH values (X +/- 2 SD) were 34 +/- 19% for adult cells (n = 29) and 14 +/- 19% for cord cells (n = 19); the difference was significant (P less than 0.0001). By pretreatment of these cells with trypsin the C3d AH was either completely abolished or markedly reduced. Its difference between the adult and cord cells was eliminated as the observed values were 4 +/- 7% and 3 +/- 4% respectively (P = 0.15). The supernatant fluid of cell-trypsin mixture, treated with trypsin inhibitors, was found to be inhibitory to C3d AH but not to C3c AH. In contrast, the AH of C3d-coated red blood cells resulting from complement fixation in vivo (ie, cold agglutinin disease) or in vitro (eg, sucrose water reaction) was resistant to trypsin treatment. The difference between the trypsin-sensitive and trypsin-resistant cell-bound C3d is postulated to be at its attachment mechanism to the cell membranes. In addition, both the advantage and limitation of using trypsinised cells for C3d antiglobulin tests are demonstrated.

Adult↗

PubMed1987

Virulence-plasmid is associated with the inhibition of opsonization in Yersinia enterocolitica and Yersinia pseudotuberculosis.

Plasmid-cured variants of virulent strains of Yersinia enterocolitica and Y. pseudotuberculosis were obtained by selection after growth in calcium-deficient medium. To obtain antigen preparations consisting of whole bacteria the original plasmid-containing strains and the plasmid-cured variants were grown in conditions favouring expression of the temperature-inducible outer membrane proteins of Yersinia (YOP) (37 degrees C, calcium-deficient culture medium). The presence or absence of the YOP on the bacteria was verified by immunoblotting. Opsonophagocytosis of YOP-negative Yersinia preparations (YOP-) was compared to that of YOP-containing ones (YOP+) in human polymorphonuclear leukocyte (PMN) chemiluminescence (CL) assay. The attachment of complement C3b on the surface of the bacteria after opsonization with normal human serum was determined by using a fluorescent anti-C3c-antibody and flow cytometry. YOP+ bacteria resisted opsonization in the absence of specific antibodies, as indicated by diminished C3b-fixation on bacteria and weaker CL response. This implies that virulence-plasmid-coded structures provide Y. enterocolitica and Y. pseudotuberculosis with an ability to avoid complement-mediated opsonization and phagocytosis.

Bacterial Outer Membrane Proteins↗

PubMed1989

[Atopic dermatitis. II. The status of complement proteins and the pathogenetic role of anaphylatoxins C4a, C3a and C5a].

Eighty-eight patients with atopic dermatitis have been examined for the complementary proteins C3 (C3c), C3act., C4, C1inact. by radial immunodiffusion; in 36 of these patients anaphylatoxins C3a des Arg, C5a des Arg, and C4a des Arg have been radioimmunoassayed. Increased levels of C4a des Arg have been revealed in 50% of the examinees. C3a des Arg levels did not differ significantly from the reference values, and C5a des Arg level has been within the normal range in all the patients. C4a des Arg has been related to the severity of the skin inflammation and did not depend on the serum IgE content. C3 (C3c), C3act., C1inact. have been elevated and C4 reduced. These findings evidence activation of the complementary system in atopic dermatitis and indicate the role of anaphylatoxin C4a des Arg in the maintenance of the inflammatory reactions.

Adolescent↗

PubMed1983

Absence of complement activation in vitro by sodium meglumine ioxitalamate.

The effect of radiographic contrast media on proteins of the complement system in vitro was investigated using protein level measurement and crossed immunoelectrophoresis. Despite the 20% loss of total serum hemolytic activity (CH50) induced by sodium meglumine ioxitalamate (0.5 M), no significant changes in C3c, C3N or B were detected by radial immunodiffusion. These contrast media did not cause electrophoretic conversion of C3, as assessed by the absence of split product, and the small degree of spontaneous C3 conversion (loss of 20% C3N antigen and the presence of two peaks with C3c antigen) which occurred when serum was incubated in polypropylene tubes, was inhibited by the contrast media. The effects of sodium meglumine ioxitalamate and zymosan in vitro on complement activation were compared.

Blood Proteins↗

PubMed1998

Interactions between Candida species and platelets.

Candida spp. are able to cause disseminated disease in immunocompromised patients. This study examined the interactions of Candida spp. with platelets, complement and polymorphonuclear leucocytes (PMNLs). With the exception of C. albicans, all other Candida spp., including a C. albicans strain previously classified as C. stellatoidia, aggregated human platelets at a ratio of yeast cells: platelets of 1:80. Usually, those species and strains that aggregated platelets were either killed or prevented from growing in platelet-rich plasma indicating that the aggregation released microbicidal or microbistatic substances that were active against Candida spp. All Candida spp. were resistant to attack by complement in 50% serum. However, all species activated complement as determined by the presence of C3 fragments on their surface, in particular a 195-kDa fragment corresponding to C3c, two fragments at 67 and 40 kDa corresponding to iC3b, and a 33-kDa fragment corresponding to C3d. When strains were tested for their ability to stimulate the release of pro-inflammatory substances from platelets and PMNLs, it was found that most strains stimulated PMNLs to release interleukin(IL)-8 but not IL-1beta or leucotriene B4. The ability of C. albicans to evade complement-mediated killing and not to aggregate platelets may contribute to the survival of this species in the blood during vascular infections.

Anticoagulants↗