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PubMed1993

Complement and leukocyte activation in septic baboons.

The effect of Escherichia coli infusion on complement and leukocytes was evaluated in a baboon model. During 8 hr, different amounts of live E. coli (5 x 10(8), 2.5 x 10(9) and 10(10) live bacteria kg body weight) were infused. Twenty-one baboons were investigated. Activation of complement (terminal C5b-9 complement complex; TCC) and activation of leukocytes (PMN elastase) and plasma concentrations of endotoxin (lipopolysaccharide; LPS) were determined before the start of bacteria infusion and 2, 4, 6, and 8 hr after the start of infusion. In baboons receiving 2.5 x 10(9) and 10(10) live E. coli per kilogram body weight, increasing plasma levels of TCC were found (P < 0.05). No significant alterations of TCC were observed when animals were infused with 5 x 10(8) live E. coli per kilogram body weight during an 8 hr period. Plasma levels of PMN elastase increased significantly in baboons receiving 5 x 10(8), 2.5 x 10(9), and 10(10) live bacteria per kilogram body weight. High levels of LPS were detected in animals receiving 10(10) live E. coli bacteria per kilogram body weight and in animals receiving 5 x 10(8) or 2.5 x 10(9) live E. coli bacteria per kilogram body weight. There was a positive correlation between the formation of TCC and the plasma levels of PMN elastase and LPS and between plasma levels of PMN elastase and of LPS. Activation of complement and leukocytes may contribute to the development of organ dysfunction seen in baboons infused with high amounts of live E. coli.

Animals↗
PubMed1985

Monoclonal antibodies against neoantigens of the terminal C5b-9 complex of human complement.

Assembly of the terminal C5b-C9 complement components into the cytolytic C5b-9 complex is accompanied by exposure of characteristic neoantigens on the macromolecule. We report the production and characterization of mouse monoclonal antibodies to C9-dependent neoantigens of human C5b-9. Binding-inhibition assays with EDTA-human plasma and micro-ELISA assays with purified C9 showed that the antibodies did not react with native complement components and thus confirmed the specificity of the antibodies for the neoantigens. The monoclonal antibodies did, however, cross-react with cytolytically inactive, fluid-phase C5b-9 complexes. Thus, expression of the neoantigenic determinants was not dependent on the formation of high molecular weight C9 polymers with the complex, since these are absent in fluid-phase C5b-9. Radioiodinated antibodies could be utilized in immunoradiometric assays for the detection and quantitation of C5b-9 on cell membranes. Cross-reactivities of the antibodies with C9-dependent neoantigens of several other animal species were examined and antibody clones cross-reacting with rabbit (clones 3B1, 3D8, and 2F3), sheep (clones 3D8 and 2F3) and guinea-pig (clone 3D8) neoantigens were identified. Three of four tested clones (3D8, 2F3, 1A12) precipitated C5b-9 complexes in double-diffusion assays, probably due to their interaction with multiple and repeating C9-epitopes on the terminal complexes. The monoclonal antibodies will be of value for definitive identification and quantitation of C5b-9 on cell membranes and in tissues, and for establishing immunoassays for detection and quantitation of terminal fluid-phase C5b-9 complexes in plasma.

Animals↗
PubMed1987

Generation of complement anaphylatoxins and C5b-9 by crystalline cholesterol oxidation derivatives depends on hydroxyl group number and position.

Cholesterol crystals activate the human alternative complement pathway. Loss of Factor B hemolytic activity in C2-deficient serum was comparable to that in normal human serum after incubation with cholesterol crystals. Consumption of Factor B hemolytic activity in normal serum incubated with cholesterol occurred in a time- and dose-dependent manner. The reduced capacity of crystals-absorbed serum to activate C2, but not Factor B, on fresh crystals, indicated that cholesterol mediates antibody-dependent classical pathway activation in addition to alternative pathway activation in whole serum. Cholestane triol, an oxidation derivative of cholesterol which bears three hydroxyl groups, cleaved 5-fold more C3 than cholesterol in normal human serum. Three cholesterol derivatives, each bearing two hydroxyl groups, were intermediate activators between cholesterol and cholestane triol. The compounds differed, however, in their complement-activating ability, indicating that hydroxyl position as well as number exerts an influence on complement activation. Measurements of C3adesArg and C5adesArg antigens in cholesterol crystal treated serum revealed that approx. 10% of total serum C3 was cleaved and that, on a molar basis, only 3% C5 cleavage occurred relative to C3 cleavage. For 1 mole of C5a generated, 0.1 moles of fluid-phase C5b-9 was detected. Although the extent of C3 cleavage varied with each cholesterol derivative depending on the position and number of hydroxyl groups, the relative coupling efficiency of C3 and C5 cleavage and C5a and C5b-9 generation was similar for all compounds. The ability of cholesterol and its oxidation products to generate anaphylatoxins and C5b-9 complexes may be of importance in mediating inflammatory processes involved in atherogenesis.

Anaphylatoxins↗
PubMed1993

Transient changes in erythrocyte membrane permeability are induced by sublytic amounts of the complement membrane attack complex (C5b-9).

We have previously shown that sublytic heterologous complement induces large but transient increases in erythrocyte membrane permeability. We now report that when erythrocytes are bystanders in zymosan-activated autologous serum, they increase their Na+ permeability 10-fold, indicating that autologous complement can also induce transient membrane lesions. When we isolated the effect of the C5b-9 membrane attack complex of complement by using human C5b-9 assembled from purified components, we found there was minimal lysis but efficient Na+ uptake. Suspension of the sublytically damaged erythrocytes in K+ medium caused the cells to lyse, which is consistent with the cells recruiting a compensatory K+ efflux similar to that observed when human erythrocytes were exposed to heterologous complement. Sublytic C5b-9 exposure also became lytic when extracellular Ca2+ was limited and when the cells were exposed to charybdotoxin, an inhibitor of the Ca(2+)-activated K+ channel. This indicates that Ca2+ is required for the functional termination of the C5b-9 lesion. We also show that the membrane hyperpolarization resulting from activation of the Ca(2+)-dependent K+ efflux does not influence the termination of the C5b-9 lesion. Thus, the influx of Ca2+ through the complement lesion initiates at least two apparently independent adaptive responses: (1) a process that terminates the leak; and (2) a K+ efflux that has a volume regulatory function. Our data support the potential of the sublytic C5b-9 lesion to act as a physiologic mediator for autologous erythrocytes.

Calcium↗
PubMed1981

Molecular weight of the membrane C5b-9 complex of human complement: characterization of the terminal complex as a C5b-9 monomer.

The hydrodynamic properties of the detergent-solubilized, terminal membrane complex of serum complement components C5-C9 [C5b-9(m)] were studied to obtain an estimate of its molecular weight. In a solution of Triton X-100/deoxycholate, the protein complex binds 17% Triton X-100 and 11% deoxycholate by weight. The sedimentation coefficient of the protein-detergent complex is 26 S as determined by sucrose density gradient ultracentrifugation, and gel filtration indicated a molecular radius of 11 nm. It was ascertained by electron microscopy that these hydrodynamic parameters apply to mono-dispersed C5b-9(m) complexes, which were observed as nonaggregated, hollow protein cylinders and were identical to the complement "lesions" formed on target membranes. The calculated molecular weight of the protein-detergent complex is approximately 1,286,300 to which the protein moiety contributes approximately 1,000,000. The results indicate that the C5b-9(m) complex formed on biological membranes is a monomer entity of the C5-C9 complement components.

Complement Membrane Attack Complex↗
PubMed1987

Nucleated cell killing by complement: effects of C5b-9 channel size and extracellular Ca2+ on the lytic process.

For C5b-9 channels to mediate cytolysis of a nucleated cell, a sufficient number of channels must be formed in the plasma membrane to override the compensatory mechanisms that nucleated cells might employ to survive. It is well known that nucleated cells are relatively resistant to lysis by complement in comparison to erythrocytes, and it is now evident that this resistance is due, in part, to the ability of nucleated cells to rapidly eliminate C5b-9 from the cell surface. The ability of nucleated cells to eliminate complement complexes is related to physiochemical properties of the complex, such as channel diameter, which in turn affect Ca2+ fluxes that stimulate metabolic processes involved in the elimination process. Paradoxically, these same channel properties that stimulate the defense response may also be responsible for the lethal effects of complement. To further study the role of channel size on cytolysis of nucleated cells by C5b-9, we examined the lytic efficiency of larger C5b-9 channels containing several C9 molecules in comparison with smaller C5b-9 channels containing fewer C9. We have obtained data to indicate that although the larger channels were more cytolytically potent, the channel size had little influence on the rate of cell death. In contrast, the rate of lysis of erythrocytes was substantially slower when smaller C5b-9 channels were present. In evaluating the effect of the extracellular Ca2+ concentration, [Ca2+]o, on nucleated cell lysis in the presence of a lytic number of C5b-9 complexes, it was observed that when the [Ca2+]o was increased the rate of cell death also increased. These findings suggest that lysis of nucleated cells by C5b-9, unlike erythrocytes, may not be entirely due to colloid osmotic deregulation.

Animals↗
PubMed1989

The pathobiology of the terminal complement complexes.

C5b and the other late-acting complement components can assemble the two terminal complexes (TCC) C5b-9 and SC5b-9. In addition to the lytic effects of C5b-9 it has been demonstrated that sublytic amounts of C5b-8 or C5b-9 can stimulate several important cellular activities. These effects may be important to explain the role of C5b-9 in the production and progression of several pathological conditions that has been demonstrated in experimental models of disease. With the help of antibodies that specifically recognize C9 neoantigens, deposits of TCC have been identified in human tissues, not only in immunological diseases but also in certain nonimmunological diseases. In the latter it has been shown that often there is no concordance between deposits of TCC and those of immunoglobulins and C3. Methods for measuring SC5b-9 in biological fluids have also been developed. Normal plasma was found to have low levels of SC5b-9. Increased plasma levels of SC5b-9 have been observed during the active phase of SLE nephritis, in certain infections and during cardiopulmonary bypass. Increased levels were also found in the cerebrospinal fluid of patients with inflammatory diseases of the central nervous system and in the synovial fluid of patients with rheumatoid arthritis. Autoantibodies to C9 neoantigens in plasma of certain patients with autoimmune, infectious or neoplastic diseases have recently been recognized. Additional work is needed to better delineate the potential usefulness of these findings for diagnosis and evaluation of disease activity.

Adult↗
PubMed1994

Reduced complement and granulocyte activation with heparin-coated cardiopulmonary bypass.

Plasma concentrations of the complement activation products C3b, iC3b, and C3c; the terminal C5b-9 complement complex; and the granulocyte proteins calprotectin, myeloperoxidase, and lactoferrin were assessed in two groups of patients undergoing aortocoronary bypass procedures. In 10 patients operated on, the bypass circuits were coated by the Carmeda Bio-Active Surface and systemic heparinization was reduced to 1.5 mg/kg; in another 10, the systems were uncoated and the dosage of systemic heparinization was 4 mg/kg. In both groups, significant complement activation was observed after the onset of cardiopulmonary bypass, but the maximum levels of C3b, iC3b, and C3c and the terminal C5b-9 complement complex were significantly lower in the heparin-coated group. In both groups, a significant increase in calprotectin, myeloperoxidase, and lactoferrin release was observed by the end of operation. The maximum myeloperoxidase levels were significantly lower in the heparin-coated group than those in the uncoated group (p = 0.03). There was a correlation of borderline significance between the formation of terminal C5b-9 complement complex and lactoferrin release, as well as between the formation of terminal C5b-9 complement complex and myeloperoxidase release (p = 0.05). The postoperative blood loss did not differ significantly between the two groups. We conclude that coating by end point-attached and functionally active heparin allows a significant reduction in the amount of systemic heparinization, and significantly reduces complement and granulocyte activation.

Aged↗
PubMed1978

Complement lysis: evidence for an amphiphilic nature of the terminal membrane C5b-9 complex of human complement.

The terminal, membrane-derived C5b-9 complex of human complement (C) is an apparently hollow, cylindrical macromolecule vertically oriented on the target membrane. In the present study, an antiserum to the complex has been used to probe its immunobiochemical properties. "Neoantigenic" determinants characteristic of the complex have been detected, which are absent on native C5-C9 molecules. Evidence that the C5b-9 complex is an amphiphilic molecule that possesses apolar, detergent-binding surfaces has been obtained by using charge-shift crossed immunoelectrophoresis, and by direct demonstration of Triton X-100 binding to the complex in quantitative immunoelectrophoresis. By the same criteria, serum C5, C6, and C9 are hydrophilic molecules. The results indicate that assembly of C5-C9 into the terminal membrane C5b-9 complex is accompanied by conformational changes in the individual C components that lead to the exposure of apolar molecular regions in the complex. It is proposed that this constitutes the basis for the lipid-binding properties of the macromolecule, which enable it to become inserted into biologic and artificial lipid membranes with apparent generation of a transmembrane pore.

Animals↗
PubMed1981

Proteolysis of the monomeric and dimeric C5b-9 complexes of complement: alteration in the susceptibility to proteases of the C9 subunits associated with C5b-9 dimerization.

The C5b-9 monomer having the sedimentation coefficient of 23S was extracted from the rabbit erythrocyte membranes that had been treated with a limiting amount of C9-deficient human serum and of 125I-C9. Upon proteolysis by trypsin and chymotrypsin, the C9 subunits of this complex were cleaved by these enzymes at multiple sites, yielding fragments with m.w. ranging fro 40,000 to 19,000. The uncomplexed C9 was also cleaved by both enzymes at multiple sites. By contrast, the C9 subunits of the C5b-9 dimer were found to be totally insusceptible to chymotrypsin under the conditions studied (37 degrees C; 24 hr) and only partially susceptible to trypsin (33% of the C9 subunits were cleaved by trypsin into 2 fragments during incubation at 37 degrees C for up to 24 hr). Therefore, these results indicate that, although the binding of C9 molecules to the C5b-8 complex (C5b-9 monomer formation) does not significantly affect the susceptibility to proteases of the C9 molecules, C5b-9 dimer formation markedly limits the accessibility of proteases to the C9 subunit molecules. A implication of this finding to a role for C9 in C5b-9 dimerization is discussed.

Animals↗
PubMed1986

Immunohistochemical study of the C5b-9 complex of complement in human kidneys.

The presence and localization of the C5b-9 neoantigens of the terminal complement sequence, of antigens expressed by cleavage fragments of C3, and of Factor H antigens have been studied by immunohistochemical techniques in morphologically normal adult human kidneys and in biopsy specimens from patients with a wide range of renal diseases with and without immune deposits. In morphologically normal kidneys, C5b-9 neoantigens were observed within all connective matrices (arteriolar media, glomerular basement membrane (GBM), mesangial matrix and tubular basement membrane). The C3d and C3g antigens of the C3dg, and C3bi cleavage fragments of C3 and Factor H antigens were found in similar locations. None of the matrices stained for immunoglobulins. Immunoelectron microscopy demonstrated that C3d, C3g, H antigens and the C5b-9 neoantigens were localized on membranous and vesicular structures embedded in the connective matrices. These structures represent cell membranes shed from adjacent cells as evidenced by their ultrastructural appearance and by the fact that those which were in close vicinity to pedicles within the GBM expressed the C3b receptor antigen, a specific marker for podocyte membranes. Formation of C5b-9 complexes in the shielded environment of connective matrices may explain their persistence over long periods of time in the absence of apparent immunopathological consequences. Biopsies from pathological kidneys were classified into three groups based on the pattern of glomerular staining with anti-C5b-9 antibodies. In the first group, a sparse mesangial labeling was seen, similar to that observed in normal kidneys. In the second group, abundant clusters of C5b-9 were seen in the same location as immune deposits. Activation of the complement system to completion could be documented in the absence of detectable C3 (C3c) antigen in glomeruli. Immunoelectron microscopy demonstrated that C5b-9 neoantigens were present on cell remnants in connective matrices in all specimens that were studied. Labeled cell remnants were present in large amounts in sclerotic matrices. C5b-9 neoantigens were constantly found on old and large immune deposits, and absent or occasionally present on recent and small immune deposits. In membranous nephropathy stage I, proteinuria appeared to be independent of the presence or absence of detectable C5b-9 neoantigens on immune deposits. Thus, the presence of C5b-9 neoantigens in pathological renal tissue does not have an univocal significance, and requires analysis of the localization of the antigens and appropriate controls in order to assess the potential role of C5b-9 in tissue damage.

Adult↗
PubMed1989

Non-enzymic activation of the fifth component of human complement, by oxygen radicals. Some properties of the activation product, C5b-like C5.

Purified human C5 was converted non-enzymically to an activated form as defined by its ability to participate in reactive lysis. This conversion occurred following exposure to systems that generate oxygen radicals, namely addition of H2O2 in the presence of ascorbic acid and iron or the addition of xanthine oxidase, acetaldehyde and iron. The conversion of C5 to a functionally active species was iron-dependent and inhibited by hydroxyl radical scavengers such as DMSO. The findings suggest that OH. is the active oxygen species that converts C5. The conversion product of C5, termed C5(H2O2), is C5b-like due to its ability to bind C6 and cause reactive lysis. C5(H2O2) is much more stable than C5b obtained by complement convertases. Although C5(H2O2) has lost the binding site of native C5 for C3b it can be cleaved by complement-derived convertases; the cleavage is, however, less efficient than in the case of native C5. The resulting cleavage product, which is C5a-like, is chemotactic although C5(H2O2) is not chemotactic. C5(H2O2) serves as a better substrate for plasma kallikrein than native C5, resulting in the generation of a C5a-like chemotactic product. These data indicate that oxygen radicals can bring about a conformational change in C5, causing it to behave as a functionally activated molecule of the complement system. This may have implications for the role of complement and its activation in the inflammatory response.

Complement Activation↗
PubMed1989

Terminal complement complex and endothelial cells.

The effects of the terminal complement sequence on two endothelial cell functions (prostacyclin (PGI2) generation and permeability of an endothelial cell monolayer) were examined in antibody-sensitized pulmonary artery endothelial cells. Whereas C5b-7 complement complexes induced on PGI2 formation and no enhanced endothelial permeability, addition of purified complement component C8 resulted in a time- and dose-dependent burst of PGI2 release and in a substantially increased permeability of an endothelial cell monolayer in the absence of overt cell damage. Formation of the complete terminal complement complex C5b-9 enhanced PGI2 release but was accompanied by cytolysis. Extracellular Ca2+ was required for C5b-8 dependent PGI2 formation. Three different blockers of physiological calcium channels failed to suppress the observed stimulatory effect. One minute after addition of C8 to endothelial cells carrying C5b-7 complexes, a six to sevenfold enhanced passive influx of 45Ca2+ into the cells was noted. An enhanced passive influx was also observed for 51CrO4(2-), 3H-aminobutyric acid, and 3H-sucrose, but not for 3H-inulin and 3H-dextran. These data together suggest that complement C5b-8 complexes may serve as Ca2+-bypass gates in endothelial cells, the ensuing influx of Ca2+ leading to subsequent activation of the arachidonic acid pathway and the actin-myosin system.

Arachidonic Acid↗
PubMed1991

Complement activation in relation to development of preeclampsia.

Six hundred eighty-five primigravidas followed as a series had complement activation evaluated by the formation of anaphylatoxins (C3a and C5a) and terminal C5b-9 complement complexes in venous blood. Samples for complement determinations were obtained four times during pregnancy, in pregnancy weeks 12-16, 20-24, 28-32, and 34-36. Seven of the women developed preeclampsia and one of them the syndrome of hemolysis, elevated liver enzymes, and low platelet count (HELLP syndrome). Eleven others with uncomplicated pregnancies were selected as a control group. Plasma samples were taken from these 18 women at delivery and 1 and 7 days after delivery. At delivery, plasma C5a levels were significantly greater in the preeclamptics than in controls, and four of the seven preeclamptics had elevated plasma C3a values compared with controls. One week after delivery, these plasma anaphylatoxins had returned to normal. Elevations of the anaphylatoxins could not be detected before the women developed clinical signs of preeclampsia. No alterations in terminal C5b-9 complement complexes could be observed in the women with preeclampsia. However, the women who developed HELLP syndrome had elevated plasma concentrations of C3a, C5a, and terminal C5b-9 complement complex at delivery. These values returned to the normal range 1 week after delivery. We conclude that complement activation in the systemic circulation does not occur early in pregnancy and that plasma concentrations of C3a, C5a, or terminal C5b-9 complement complex cannot be used as predictors of preeclampsia.

Adult↗
PubMed1993

Complement activation during liver transplantation.

Twelve patients with end-stage liver disease undergoing liver transplantation were studied regarding complement activation and formation of anaphylatoxins (C3a and C5a) and terminal C5b-9 complement complexes (TCC) after reperfusion of the grafted liver. Blood samples for complement variables (C1INH, C3, C4, C5, C3a, C5a, and TCC) were drawn preoperatively, before the anhepatic phase, 1 min before, and 2, 15, and 60 min after the start of reperfusion of the grafted liver. Activation of complement was observed during the operation. The C1INH, C3, C4, and C5 plasma concentrations decreased during the entire operation while the anaphylatoxin C3a and the terminal C5b-9 complement complex increased after the reperfusion of the grafted liver. Activation of complement with the formation of biologically active substances like anaphylatoxins and terminal C5b-9 complement complexes may be one explanation for circulatory complications often seen in patients undergoing orthotopic liver transplantation.

Adult↗
PubMed1975

On the mechanism of cytolysis by complement: evidence on insertion of C5b and C7 subunits of the C5b,6,7 complex into phospholipid bilayers of erythrocyte membranes.

The doughnut hypothesis of cytolysis by complement [Mayer, M. M. (1972) Proc. Nat. Acad. Sci. USA 69, 2954-2958] describes an annular structure made up of C5b-9 (complement factors C5b, C6, C7, C8, and C9) which becomes inserted in the lipid bilayer of the cell membrane, thus creating a hole. We now present initial explorations of this hypothesis. EAC1-6 and EAC1-7 (sheep erythrocytes carrying rabbit antibody and complement factors C1 through C6 or C1 through C7, respectively), prepared with either 125I-C3 or 125I-C5 were incubated with trypsin and the release of bound 125I was measured. In the case of 125I-C3, all of the radioactivity was released by trypsin from both intermediates. With 125I-C5, trypsin released all of the 125I from EAC1-6, but only 40-55% from EAC1-7. Possible reasons for resistance of the C5b subunit in EAC1-7 to tryptic digestion are discussed; in terms of the doughnut hypothesis it would be due to shielding by lipid molecules as a consequence of insertion into the lipid bilayer. In accord with this interpretation we have also found that C5b in EAC1-7, but not in EAC1-6, resists elution by 0.3 M NaC1. Similarly, we have found that 125I-C7 in EAC1-7 resists stripping by trypsin. Hence, we now propose the hypothesis that hydrophobic polypeptide chains from the C5b and the C7 subunits of C5b,6,7 complex become inserted in the phospholipid bilayer and that subsequent reactions with C8 and C9 open a channel across the membrane.

Animals↗
PubMed1983

Studies of the mechanism of bacterial resistance to complement-mediated killing. V. IgG and F(ab')2 mediate killing of E. coli 0111B4 by the alternative complement pathway without increasing C5b-9 deposition.

The mechanism of antibody-dependent complement-(C) mediated killing of Escherichia coli 0111B4, strain 12015 (12015), was examined. 12015 was resistant to serum killing when incubated in hypogammaglobulinemic serum (H gamma S) or pooled normal human serum (NHS) that had been previously adsorbed to remove specific antibody (Abs NHS). Presensitization with immune rabbit serum or purified immune rabbit IgG resulted in 1 to 3 log killing when 5 X 10(8) colony forming units (CFU)/ml were incubated in 10 to 40% Abs NHS. Binding of 125I-C3 and 131I-C9 to the bacterial surface of the presensitized and the nonpresensitized strain was quantitated when these organisms were incubated in 10, 20, and 40% Abs NHS. Stable binding of up to 3.0 X 10(5) molecules of C3 and 8.0 X 10(4) molecules of C9 to presensitized and nonpresensitized isolates occurred in the highest concentration of serum, but there was no killing without presensitization. Similar results were found when Abs NHS was chelated with ethylene bis glycoltetraacetic acid containing 2 mM MgCl2 (Mg EGTA) to block classical pathway activation, indicating that antibody mediated the bactericidal reaction through the alternative pathway. Deposition of C3 and C9 and killing of 120 15 in 10% Abs NHS or 10% H gamma S was measured after presensitization with increasing amounts of IgG, F(ab')2, or Fab'. There was a dose-dependent increase in C3 deposition and killing, but only minimal change in C9 binding when 1.0 X 10(3) to 3.2 X 10(4) IgG or F(ab')2/CFU were bound to the bacterial surface. In contrast, there was no increase in C3 or C9 binding and no bacterial killing when 1 X 10(3) to 3.4 X 10(4) molecules Fab'/CFU were bound to the bacterial surface. These experiments show that immune IgG and F(ab')2 can mediate killing of E. Coli 0111B4 by the alternative pathway without changing the extent of terminal C component attachment to the bacterial surface.

Animals↗