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V Brade

Publications and source records attributed to V Brade.

At least 19 recordsLinked to original sources
PubMed1992

Differences of two Borrelia burgdorferi strains in complement activation and serum resistance.

Complement activation and serum resistance of the Borrelia burgdorferi strains B31 (American strain) and PKo (European strain) were compared. In 25% (v/v) normal human serum (NHS) free of B. burgdorferi-specific antibodies the cells of the PKo strain were high activators of complement as indicated by rapid and strong C9 consumption, by deposition of up to 336763 C9 molecules per cell and by the formation of the terminal complement complex on the cell surface. By comparison, complement activation by the B31 strain was low with 5.4-fold less C9 deposited per cell. The addition of B. burgdorferi-specific antibodies to NHS either as purified IgG or heat-inactivated patient sera, had no influence on the results with both strains. After an incubation period of 2h at 37 degrees C in 25% (v/v) NHS most cells of the PKo strain had lost their viability as indicated by cell immobilization and failure to multiply in subcultures. In addition, extensive cell fragmentation and bleb formation were observed in the electron microscope. In contrast, the B31 strain remained alive and morphologically intact after the same incubation with NHS. We conclude from our results that complement activation and serum resistance are properties which differ considerably between isolated strains of B. burgdorferi.

Antibodies, Bacterial↗
PubMed1992

Mechanism of YadA-mediated serum resistance of Yersinia enterocolitica serotype O3.

Complement activation via the alternative pathway was analyzed with isogenic strains of Yersinia enterocolitica serotype O3 differing in plasmid content (p- or p+ strains) or selective lack of YadA expression (YadA- strain). The p+ strain was serum resistant, even after antibody-enhanced complement activation. Serum sensitivity was observed with the p- and YadA- strains but was more pronounced in the p- strain. The p+ strain deposited less C5b-9(m) complexes on its surface than the p- and YadA- strains. No size difference, however, was detected with solubilized C5b-9(m) complexes obtained from resistant and sensitive strains. At the C3 level, it became evident that surface-bound C3b was degraded faster into iC3b on the p+ strain than on the p- and YadA- strains. Our results demonstrate that YadA inhibits complement activation at the C3 and C9 level. As a result, reduced amounts of C5b-9(m) are generated on the surface of YadA-bearing bacteria. In addition, YadA seems to protect against the lytic action of those C5b-9(m) complexes whose deposition could not be prevented.

Adhesins, Bacterial↗
PubMed1991

T cell proliferation induced by Borrelia burgdorferi in patients with Lyme borreliosis. Autologous serum required for optimum stimulation.

The cellular immune response to Borrelia burgdorferi was studied in 24 patients with seropositive and seronegative Lyme borreliosis, 30 patients with arthritides of different origin (non-Lyme arthritides), and 20 normal blood donors. By far, the strongest T cell stimulation was induced by incubation with autologous serum; there was a significantly lower response or no response after incubation with allogeneic or heterologous sera. In patients with Lyme borreliosis, including seronegative patients, there was a strikingly elevated proliferation in response to whole B burgdorferi bacteria (mean 64,750 dpm) compared with that of normal donors (mean 19,700 dpm; P less than 0.0001) and especially that of non-Lyme arthritis patients (mean 11,600 dpm; P less than 0.0001). Levels of proliferation declined significantly in patients with Lyme borreliosis after successful antibiotic treatment. Parallel cultures using B burgdorferi and Treponema phagedenis as antigens showed that cells from patients with Lyme borreliosis responded significantly more to B burgdorferi than to T phagedenis, but this did not occur with cells from individuals with non-Lyme arthritides. There was no correlation between disease stages and proliferation values. These data indicate that lymphocyte proliferation assays may provide an important tool for the diagnosis of Lyme borreliosis, most notably in patients with arthritides and in those who are seronegative. Conversely, the lack of reactivity appears to be a strong indicator of the absence of active Lyme disease. It seems to be crucial, however, to use autologous sera in these assays.

Adolescent↗
PubMed1991

Evasion of Yersinia enterocolitica serotype 03 from complement-mediated killing.

Using isogenic strains of Y. enterocolitica serotype 03 (isolate 75) differing in LPS side chains (S and R), plasmid content (p+ and p-) or selective failure of YOP1 expression (YOP1-) we observed comparable C9 consumption via the alternative pathway by all strains. Differences became apparent in the bactericidal assays in which the 75S p+ strain was resistant whereas the plasmid-negative S and R strains were killed. Increased but submaximal resistance was observed with the 75R p+ and 75S YOP1- strains indicating that LPS side chains and plasmid-encoded factors other than YOP1 also contribute to serum resistance. Deposition of C9 and terminal complement complex (TCC) formation were greatly reduced on the resistant 75S p+ strain compared to the sensitive 75S p- strain. The 75S YOP1- variant behaved like the 75S p- strain with respect to C9 deposition and TCC formation suggesting that YOP1 prevents terminal C activation. A comparison of TCC deposited on resistant and sensitive Y. enterocolitica revealed no differences with respect to their salt- and protease-resistance and their size. We conclude from our experiments that serum resistance of 75S p+ depends on several surface components YOP1 being the most important. The YOP1 protein clearly interferes with C9 deposition and TCC formation and thereby contributes to serum resistance of plasmid-positive, YOP1 expressing Y. enterocolitica.

Centrifugation, Density Gradient↗
PubMed1979

[Complement: function. Biological significance and clinical aspects (author's transl)].

The term complement comprises approximately twenty serum proteins. Activation of these components can be started by antigen-antibody complexes or even without the participation of antibodies. The activated complement proteins bring about a number of important biological actions. They produce vigorous local inflammatory reactions, exert phagocytosis--increase effects, destroy microbial and animal cells and affect the immune response to antigen stimulus. Congenital lack of individual complement components may considerably impair the antimicrobial defense or even be the cause of excessive inflammatory reactions. The activation of complement may also have harmful effects on the organism.

Angioedema↗
PubMed1978

Requirements for the solubilization of immune aggregates by complement. The role of the classical pathway.

In this paper we examine the role of the classical pathway in the complement-mediated solubilization of immune precipitates (CRA). Serum reagents were depleted of the alternative pathway components properdin and factor D. Both depleted reagents lack CRA although they have almost intact hemolytic activity. Also, immune complexes were not solubilized when incubated with high concentrations of the classical pathway components (C1, C4, C2, and C3. We conclude that CRA is not mediated by the classical pathway alone. Activation of the classical pathway by the immune aggregates greatly enhances CRA. The effect of the classical pathway is to deposit C3b on the antigen-antibody lattice and promote the assembly of a lattice-associated, properdin-dependent C3-convertase. Although C3, C4, and properdin were detected on complexes solubilized by serum in the presence of Ca++ and Mg++, only C3 and properdin were found on the complexes when Ca++ had been chelated by ethylene glycol-bis-(beta-aminoethyl ether), N,N'-tetraacetic acid. In both situations the aggregates were capable of converting C5 in the fluid phase. However, no C5 was found on the solubilized complexes. These findings suggest that in contrast to nascent C3b and C4b, nascent C5-9 lacks binding affinity for immune aggregates.

Antigen-Antibody Complex↗
PubMed1977

Biosynthesis of pro-C3, a precursor of the third component of complement.

A precusor of the third component of complement, pro-C3, was detected in studies of cell-free synthesis and intracellularly in homogenates of liver tissue cultures. The molecular weight of pro-C3 was indistinguishable from that of intact native C3 secreted in vitro by liver or peritoneal macrophages, but its structure was different. Pro-C3 is a single polypeptide chain, whereas C3 secreted by cells in culture consists of two polypeptide chains (mol wt 120,000 and 76,000) linked by disulfide bonds.

Animals↗
PubMed1977

Effect of in vivo stimulation of mice on the secretion of factor B of the alternate complement pathway by peritoneal macrophages.

After in vivo treatment of mice with thioglycollate medium, the amount of native factor B which could be detected in vitro in culture supernatants of peritoneal macrophages was much lower than that found in supernatants of macrophages taken from untreated mice. However, when the macrophages from thioglycollate medium-treated mice were cultured on a plastic surface covered with glutardialdehyde-linked bovine serum albumin, the culture supernatants contained larger quantities of native factor B than culture supernatants of macrophages from untreated mice under the same conditions. Thus, the effect of in vivo thioglycollate medium treatment on the in vitro secretion of factor B by peritoneal macrophages could be modulated by the culture conditions. Factor B in culture supernatants of macrophages obtained from both untreated and thioglycollate medium-treated mice was stable. It remained functionally active, and therfore uncleaved over a long incubation period at 37 degrees C. In addition, factor D activity was never detected in any culture supernatant.

Animals↗
PubMed1977

Interaction of zymosan and of activated properdin with factor D-depleted guinea pig serum: implications for the mechanism of initial C3 cleavage via the alternative complement pathway.

Factor D of the alternative C pathway was specifically removed from guinea pig serum. The resulting serum reagent (RD) supported neither the formation of a C3-cleaving enzyme on zymosan (Z) nor the inactivation of C3 or of factor B in the presence of Z or activated properdin (P). Addition of purified D to RD restored these properties. Studies were limited amounts of purified D were added to RD with Z or P as activating substances, gave the following results: (1) Inactivation of B and of C3 occurs in the presence of minute amounts of D. (2) C3 inactivation is more efficient than B inactivation and proceeds even in the absence of detectable enzymatic B activation. (3) C3 cleavage at any D concentration tested is always accompanied by uptake of C3 fragments onto Z. With respect to initial C3 cleavage via the alternative C pathway these data suggest that the initiating reaction is D-dependent, very efficient in depositing C3 fragments on particulate activating substances such as Z and able to utilize factor B in an apparently uncleaved form.

Animals↗
PubMed1977

Inherited polymorphism of guinea pig factor B and C4: evidence for genetic linkage between the C4 and Bf loci.

An inherited structural polymorphism of the guinea pig complement protein C4 and of factor B of the alternative pathway was demonstrated by use of high voltage agarose electrophoresis combined with a subsequent immunofixation technique. No polymorphism of guinea pig C3 could be shown. Three common allelic genes were proven to code for C4-S, C4-S1, and C4-F, respectively. Two common allelic genes are responsible for the Bf-F and Bf-S phenotype expression. A strong linkage disequilibrium between both C4 and Bf was demonstrated.

Animals↗
PubMed1976

In vitro synthesis of factor B of the alternative pathway of complement activation by mouse peritoneal macrophages.

Factor B of the alternative pathway of complement activation was shown to be synthesized and secreted by unstimulated mouse peritoneal macrophages. The activity of B in the culture supernatants from macrophage monolayers was detected by consumption of C3 in reaction mixtures containing supernatant and guinea pig factors C3, D and insoluble C3b. Using a monospecific antiserum, factor B in concentrated culture supernatants was shown by immunodiffusion and immunoelectrophoresis to be identical to factor B in mouse plasma and to form a characteristic complex with cobra venom factor in the presence of D. A steady rate of factor B secretion was observed for 4 days providing the medium was changed every 24 h. Cycloheximide (0.5 mug/ml), an inhibitor of protein synthesis, caused inhibition (90%) of factor B production. Incubation of culture medium containing 14C-labeled amino acids with the macrophage monolayer resulted in incorporation of radioactivity into factor B as detected by autoradiography of precipitation lines formed with anti-B antiserum; This indicated that synthesis of factor B had occurred. In the same culture supernatants the presence of newly synthesized C3 was also demonstrated.

Animals↗
PubMed1976

Incompatibility between C3b and B of guinea-pig and man and its influence on the titration of the alternative pathway factors D and B in these two species.

The incubation of the proteins C3b, B, D and C3 induces enzymatic activation of B and of C3. This system of purified components was applied to the titration of the guinea-pig and human factors D and B in various homologous and heterologous reaction mixtures. On the basis of functional as well as of immunological tests, the D enzymes of both species were found to be related proteins. First, titrations of factor B revealed that both D enzymes activate homologous and heterologous B with comparable efficiency. Secondly, a rabbit anti-D antiserum raised against guinea-pig D was found to form a precipitation line of partial identity with guinea-pig and human D. In contrast to the compatibility between heterologous D and B, heterologous combinations of C3b and B were found to be incompatible. This incompatibility was indicated by low titres of D in the presence of heterologous C3b and B; in contrast, in the presence of homologous C3b and B, the titres of D were up to one hundred-fold higher. The reason for this effect was found to reside in inefficient complex formation between heterologous C3b and B. Therefore titrations of D and B should be only performed in the presence of homologous C3b and B.

Animals↗
PubMed1976

Mouse factor B of the alternative pathway of complement activation. I. Purification, characterization, and functional behavior.

Mouse factor B was purified and a monospecific antiserum was raised. The physicochemical data of this protein (108,000 m.w., 5.9 S, 5.9 to 6.05 isoelectric point) were determined. The functional behavior resembles that of human and guinea pig factor B and it operates efficiently in the C3 feedback cycle of the alternative pathway of complement activation. A provisional scheme is given for the operation of the C3bB enzyme on the cellular (macrophage) level.

Animals↗
PubMed1975

Dextran sulphate: a synthetic activator of C3 via the alternative pathway. I. Influence of molecular size and degree of sulphation on the activation potency.

The polyanion dextran sulphate (DS) triggers the alternative pathway of complement. The influence of the molecular weight and degree of sulphation on this potency was studied. The degree of substitution turned out to be the critical parameter for optimal C3 turnover: 60 SO4/100 glucose units (Glc) showed optimal activity; an increase up to 190 SO4/100 Glc did not increase the activation potency, while lowering the degree of sulphation diminished this activity. DS preparations (120 SO4/100 Glc) of molecular weight: 1 x 10(4); 8 x 10(4); 2-5 x 10(5); 2 x 10(6) were equally active; a DS of molecular weight 5 x 10(3) was inactive. These results indicate that above a critical molecular size (greater than 5 x 10(3)) only the degree of substitution is responsible for the C3 activating capacity. Clusters of several glucose residues each carrying one or two sulphate groups are thought to be the essential structure in DS for the activation of the alternative pathway.

Animals↗
PubMed1975

Interaction of C3b, B, and D in the alternative pathway of complement activation.

The interaction of ZXd2, an insoluble intermediate of the alternative pathway on zymosan (Z5), with factor B and the enzyme D proceeds in a two-step reaction: 1) B binds in the presence of Mg++ to ZXd2 to form the intermediate ZXd2B, 2) B bound to ZXd2 is subsequently activated enzymatically by D to yield the complex ZXd2B which cleaves C3. Evidence was obtained that C3b, which is present on ZXd2, is required for ZXd2B formation. Studies of the functional role of C3b for ZXd2B formation revealed that C3b is involved in the first reaction step i.e., binding of B to ZXd2 to yield ZXd2B. Formation of ZXd2B is inhibited by pretreatment of ZXd2 with either anti-C3 Fab or with C3b-INA. Low ionic strength of about 2 mS was found to favor the interaction of the C3b with B. Mg++ concentrations from 1 to 31 mM as well as variation of pH in the range from 6.2 to 8.5 did not greatly influence the reaction of B with ZXd2. For the enzymatic activation of B only C3b on ZXd2 and factor D are required. This is concluded from the finding that fluid phase C3b is sufficient for the activation of B in the presence of D. This does not exclude the fact that other proteins present on ZXd2 may help to stabilize the intermediate ZXd2B or the enzymatically active complex AXd2B, or both of them.

Animals↗