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PubMedDate not supplied

Killing of rat glial cells by complement: deficiency of the rat analogue of CD59 is the cause of oligodendrocyte susceptibility to lysis.

In an effort to understand the mechanisms of complement-mediated injury of the myelin/oligodendrocyte complex in demyelinating disease, we have examined the lytic susceptibility of rat glial cells in culture. It is known that rat oligodendrocytes are extremely sensitive to the lytic action of autologous complement, whereas other cells in the same culture system, including type II astrocytes which derive from the same progenitor cell, are relatively insensitive. Here we demonstrate that the complement sensitivity of oligodendrocytes is associated with a lack of expression of a complement-regulatory protein, the rat homologue of human CD59, and that complement resistance can be restored by the incorporation of purified rat CD59 into the cell membrane. Furthermore, neutralisation of rat CD59 on complement-resistant astrocytes renders them susceptible to lysis. Immature oligodendrocytes were resistant to complement attack yet did not express CD59, suggesting that a complement-activating factor appears on the membrane during oligodendrocyte maturation.

Animals↗
PubMed2005

Differential effect of heparin coating and complement inhibition on artificial surface-induced eicosanoid production.

BACKGROUND: Contact between blood and artificial surfaces induces an inflammatory response including activation of leukocytes and platelets, as well as complement and other plasma cascade systems. In the present study we investigated the roles of complement and surface modification in polyvinyl chloride-induced synthesis of eicosanoids (arachidonic acid metabolites). METHODS: Human whole blood was incubated in rotating loops of polyvinyl chloride or heparin-coated polyvinyl chloride tubing for 4 hours. Plasma concentrations of the eicosanoids leukotriene B4, prostaglandin E2 and thromboxane B2 were quantified. RESULTS: Polyvinyl chloride induced a substantial increase in leukotriene B4, prostaglandin E2, and thromboxane B2. Inhibition of complement activation by the complement factor 3 binding peptide compstatin or blockade of the complement factor 5a receptor with a specific antagonist significantly and specifically inhibited the synthesis of leukotriene B4, whereas thromboxane B2 and prostaglandin E2 synthesis were apparently complement independent. The increase in all three mediators was significantly reduced by the heparin coating. Indomethacin abolished the increase of the cyclooxygenase products prostaglandin E2 and thromboxane B2, but had no effect on the increase of the lipoxygenase product leukotriene B4, consistent with the specificity of indomethacin for the cyclooxygenase and confirming the specificity of complement inhibition. CONCLUSIONS: Polyvinyl chloride-induced increase in all three eicosanoids was attenuated by heparin coating, whereas complement inhibition selectively reduced the synthesis of leukotriene B4.

Complement Inactivator Proteins↗
PubMed2004

Towards a model to explain the intragenic complementation in the heteromultimeric protein propionyl-CoA carboxylase.

Mutations in the PCCA or PCCB genes coding for alpha and beta subunits of propionyl CoA carboxylase can cause propionic acidemia. To understand the molecular basis of the intragenic complementation previously reported at the PCCB locus, we now examine the complementation behaviour of four carboxy-terminal and 11 amino-terminal naturally occurring mutant alleles both using cell fusion and reconstructing the complementation event by transfecting the mutant cDNAs to generate multimeric hybrid proteins. Alleles carrying mutations p.R410W and p.W531X are able to complement with 10 out of 11 amino-terminal mutations assayed. Only the unstable p.R512C, p.L519P and p.G112D mutants fail to complement. The results analyzed in the framework of the crystal structure of the homologous 12S transcarboxylase from Propionibacterium shermanii show that all mutant alleles studied are located at beta subunits interfaces, complementing alleles at the inter-trimer interface, where the catalysis probably happens, and non-complementing alleles at the intra-trimer interface, probably disrupting the trimer formation. Our results also show a remarkable stabilization effect when p.R410W is cotransfected with p.G246V. We propose a model for intragenic complementation requiring the production of two different beta subunits carrying carboxy and amino-terminal mutations that allow regenerating functional active sites and in which a stabilization effect between subunits could be relevant to ameliorate the biochemical phenotype of each mutation separately.

Amino Acid Metabolism, Inborn Errors↗
PubMed2003

Nontransgenic hyperexpression of a complement regulator in donor kidney modulates transplant ischemia/reperfusion damage, acute rejection, and chronic nephropathy.

Complement activation during ischemia and reperfusion contributes to the development of tissue injury with severe negative impact on outcomes in transplantation. To counter the effect of complement, we present a strategy to deliver a novel complement regulator stabilized on cell surfaces within donor organs. The membrane-bound complement regulator is able to inhibit complement activation when the donor organ is revascularized and exposed to host-circulating complement. Application of this construct to donor kidneys protected transplanted tissues from ischemia/reperfusion injury and reduced the deposition of activated complement and histological signs of damage under conditions in which a nontargeted control construct was ineffective. Treatment of donor organs in this way improved graft performance in the short and long term. An analysis of the immune response in allograft recipients showed that reducing graft damage at the time of transplantation through complement regulation also modulated the alloresponse. Additionally, the results of perfusion studies with human kidneys demonstrated the feasibility of targeting endothelial and epithelial surfaces with this construct, to allow investigation in clinical transplantation.

Acute Disease↗
PubMed2002

Complement 3 deficiency and oral prednisolone improve strength and prolong survival of laminin alpha2-deficient mice.

Complement deposition and macrophages are common in biopsies of children with muscular dystrophy. While the presumed roles of complement and macrophages have been those of scavenger to remove and clear necrotic fibers, there is some evidence that they play a primary role in the pathogenesis of these diseases. Here, we explore the role of complement in the pathogenesis of the most severe animal model of congenital dystrophy, the dy-/- mouse, which is laminin alpha2-deficient. We generated animals deficient in both C3 and laminin alpha2. C3 is the third component of the complement cascade and is required for activation of either the classical or alternative pathways. Thirty-three percent of the dy-/-:C3+ mice (n=59) died before 24 weeks while only 14% of the dy-/-:C3-/- (n=29) mice died (p=0.04). Absolute forepaw strength was 25-30% greater for the dy-/-:C3-/- mice up to 20 weeks of age (p<0.05 compared to complement-sufficient). Forepaw strength adjusted for weight also showed significant differences with C3-/- mice being stronger up to 20 weeks (p<0.05). However, by 24 weeks, the two groups did not differ for strength. Next, we treated 20 mice with twice weekly oral prednisolone. Survival at 24 weeks for the prednisolone treated dy-/- mice (C3-/- or C3+) was 90% (p=0.04). This work shows that complement insufficiency and weekly prednisone prolong survival and improve strength of the laminin alpha2-deficient mouse. This work suggests that the complement system may contribute directly to the pathogenesis of this form of dystrophy. Because complement activity may be modified pharmacologically, this work may have implications for treatment of children with congenital muscular dystrophy secondary to laminin alpha2 deficiency.

Administration, Oral↗
PubMedDate not supplied

Activation of the complement system as an indicator of pyrogenic reaction to lipopolysaccharide (LPS).

The generation of biologically active complement split products through the direct reaction of microorganisms with complement proteins is one of the earliest events of the defence reaction in humans. Complement activation develops within minutes, which highly corresponds with the onset of a febrile reaction after exposure to pyrogens. The possibility of the use of complement activation in human plasma as an indicator of pyrogen contamination has been tested. Additionally, the co-stimulatory effect of complement activation on tumor necrosis factor-alpha (TNF-alpha) production by blood-separated macrophages exposed to lipopolysaccharide (LPS) has been demonstrated. As an indicator of complement activation in test samples, the concentration of the iC3b fragment was measured by using an ELISA system based on neoantigen formation. The 3-h exposure time has been identified as optimal for the test. The variability between iC3b concentrations in untreated control samples obtained from seven unrelated healthy donors was less than 10%, while after activation by 100 ng/ml LPS, it increased to 13%. The lower detection limit has been identified as 10 pg/ml LPS. As the complement test is not affected by drug-cell interactions or cell viability, the test can be used in situations where tested formulations contain active substances, which interfere with a cell-based test. We conclude that a test based on the detection of complement activation in human plasma should be considered as a valuable element of an in vitro pyrogenicity testing battery along with a cell-based assay.

Animal Testing Alternatives↗
PubMed2003

Isolation of moderately infectious Borrelia burgdorferi sensu stricto from attenuated cultures by using complement-mediated, antibody-dependent lysis selection technique in a mammalian tissue co-culture system.

We investigated the association between complement resistance and phenotypes of pathogenicity of Borrelia burgdorferi sensu lato isolates cultivated in a LEW/N rat tibiotarsal joint-derived tissue feeder layer-supported co-culture system. Guinea pig complement and immune serum raised in LHS/Ss hamsters caused complete lysis of B. burgdorferi sensu stricto isolate 297, B. afzelii and B. garinii in Barbour-Stoenner-Kelly's medium; however, tissue co-cultured B. burgdorferi sensu stricto contained complement escape variants. The arthritogenicity and infectivity of these variants were tested in 3-week-old Syrian hamsters and in a vaccinated hamster model in which formalin-killed B. burgdorferi sensu stricto C-1-11 vaccinated animals develop severe arthritis after challenge with live, pathogenic, low-passage 297 isolate. Non-animal-passaged complement escape variants were infectious in both animal models as demonstrated by re-isolation from the infected animals and competitive PCR. IP injection of animal-passaged complement escape variants caused development of severe arthritis in vaccinated animals 5 weeks post-injection; animal passage of complement escape variants was necessary for isolation of arthritogenic spirochetes from high-passaged, non-arthritogenic, attenuated borrelia cultures. Complement escape variants synthesized outer surface protein E as demonstrated by SDS-PAGE and western blotting analyses. The complement-mediated selection technique in tissue co-culture provides a novel approach to the studies of Lyme disease, enables us to isolate pathogenically distinct borrelia populations from attenuated cultures and prepare a moderately infectious, non-pathogenic live vaccine against this illness.

Animals↗
PubMed2001

Mechanisms for intragenic complementation at the human argininosuccinate lyase locus.

Argininosuccinate lyase (ASL) is a homotetrameric enzyme that catalyzes the reversible cleavage of argininosuccinate to arginine and fumarate. Deficiencies in the enzyme result in the autosomal, recessive disorder argininosuccinic aciduria. Considerable clinical and genetic heterogeneity is associated with this disorder, which is thought to be a consequence of the extensive intragenic complementation identified in patient strains. Our ability to predict genotype-phenotype relationships is hampered by the current lack of understanding of the mechanisms by which complementation can occur. The 3-dimensional structure of wild-type ASL has enabled us to propose that the complementation between two ASL active site mutant subunits, Q286R and D87G, occurs through a regeneration of functional active sites in the heteromutant protein. We have reconstructed this complementation event, both in vivo and in vitro, using recombinant proteins and have confirmed this hypothesis. The complementation events between Q286R and two nonactive site mutants, M360T and A398D, have also been characterized. The M360T and A398D substitutions have adverse effects on the thermodynamic stability of the protein. Complementation between either the M360T or the A398D mutant and the stable Q286R mutant occurs through the formation of a more stable heteromeric protein with partial recovery of catalytic activity. The detection and characterization of a novel complementation event between the A398D and D87G mutants has shown how complementation in patients with argininosuccinic aciduria may correlate with the clinical phenotype.

Alanine↗
PubMed1997

A role for complement in phagocytosis of myelin.

The mechanisms for phagocytosis of myelin in cell-mediated demyelinating diseases have not been clarified. We have previously shown with cultured phagocytic cells that myelin opsonized with antiserum to myelin constituents is phagocytized in much higher amounts than untreated myelin, indicating that Fc receptors may be involved in the demyelinating process. Using various treatments of antisera, such as heating to destroy complement, and purification of IgG, we show here that complement is a necessary factor for maximal myelin phagocytosis by cultured macrophages. If myelin is sonicated to decrease its particle size, however, complement is not an active factor. Cultured microglia, on the other hand, required complement for maximal phagocytosis of both unsonicated and sonicated myelin. Addition of serum complement greatly increased phagocytosis of untreated CNS and PNS myelin, both unsonicated and sonicated, by macrophages and microglia. From these results it appears that the most important effect of complement is to fragment the myelin, making it more easily phagocytized. Prefragmentation of myelin by sonication can substitute for complement. Complement receptors may, in addition, be important for maximal myelin phagocytosis by microglia.

Animals↗
PubMed2000

Expression of complement regulatory proteins CR1, DAF, MCP and CD59 in haematological malignancies.

Host cells are protected from the lytic effect of the complement system by complement regulatory proteins. This study was designed to investigate the expression of complement regulatory proteins on leukemic blasts which may be susceptible to the lytic effects of the complement system in the circulation. The surface expressions of complement regulatory proteins, complement receptor 1 (CR1, CD35), decay accelerating factor (DAF, CD55), and homologous restriction factor 20 (HRF20, CD59), on peripheral blood and bone marrow blasts were evaluated by using flow cytometry in 16 acute myeloblastic leukemia (AML), 16 acute lymphoblastic leukemia (ALL), 4 chronic lymphocytic leukemia (CLL), 3 chronic myelocytic leukemia (CML) patients and control granulocytes and lymphocytes obtained from 15 healthy volunteers. mRNA expression was investigated by Northern blot analysis. mRNA abundances were calculated after normalization according to 28s rRNA. Surface expressions of CRI and DAF were marginally (p = 0.08 and p = 0.08, respectively) lower in AML, and DAF expression was significantly lower (p=0.0008) in ALL patients in comparison to their normal counterparts. Except from a slight increase that is detected for CD59 in CML patients (p=0.06), there was no significant difference between the surface expressions of CD59 in any of the groups studied. Densitometric analysis of autoradiographs obtained from Northern blots revealed that in AML patients, CR1 mRNA expression were 5.5-fold lower than controls (p=0.06), while DAF mRNA expression was significantly higher (p=0.0046). Furthermore, the mRNA expression of CRI in ALL patients was found significantly lower than in the control group (p = 0.0419). None of the values obtained from the other groups were significantly different from each other. These results suggest that leukemic blasts are protected from the lytic attack of the complement system at all levels, since all of the complement membrane regulatory proteins were expressed in all leukemia types (although at lower amounts in some cases), and it is also possible to use CRI and DAF as differentiation markers in acute leukemias.

Antigens, CD↗
PubMed2000

Complement: a critical test of its biological importance.

The biological activities of the more than 30 proteins that comprise the complement system have been elucidated in parallel lines of investigation that resulted in the purification of the proteins and studies of their function in vitro. Twenty years ago, the first complement cDNA clones were generated. Subsequently the structure and chromosomal localization of the complement genes and the primary sequences of their gene products were revealed. For some, even their higher order structure was solved. This work, coupled with studies of complement gene expression, biosynthesis, post-synthetic processing and secretion, contributed to an analysis of the relatively rare naturally occurring genetic deficiencies of complement proteins discovered fortuitously in humans sand experimental animals. Not until the past 5 years, with the application of methods for manipulating genes in vivo (targeted deletion and overexpression), has it been possible to definitively assign specific functions to complement proteins and to assess their importance in the intact organism. These relatively recent studies have confirmed the in vitro work or revealed unexpected roles for complement effector and regulatory proteins in host defenses, specific immunity, immunopathology, metabolism and reproductive biology This work is reviewed and the implications for understanding human diseases and the design of novel pharmaceutical agents are discussed. The promise of this line of investigation is certain but the context imposed by gender, developmental stage, other genes and environment must be taken into account before the practical implications of this deeper understanding of complement biology are fully realized.

Animals↗
PubMed1998

Establishment of complement-resistant retroviral vector by homologous restriction factor 20 gene.

Homologous restriction factor 20 (HRF20, CD59) is one of the complement regulatory factors. In this study, the complement-resistant retroviral vector, which possesses the HRF20 gene as a selection gene, was constructed and examined. The virus-producing cell, transduced with complement-resistant retroviral vector, was established after complement-dependent selection. NIH3T3 and PK15 cells transduced with this virus-producing cell were successfully selected by complement-dependent selection, which showed significant expression of the HRF20 antigen. In addition, these cells, transduced with tissue plasminogen activator (tPA) cDNA using complement-resistant retroviral vector, expressed tPA antigen after complement-dependent selection. These findings suggest that complement-resistant retroviral vector can be used for the double transduction of HRF20, as well as other genes.

3T3 Cells↗
PubMed1972

Phospholipid synthesis in HeLa cells exposed to immunoglobulin G and complement.

1. HeLa cells were cultured in the presence of heterologous immunoglobulin G and guinea-pig serum together with [(32)P]phosphate. 2. Incorporation of [(32)P]phosphate was significantly stimulated by anti-HeLa immunoglobulin G and complement-sufficient serum compared with immunoglobulin G from unimmunized rabbits and complement. Within 2.5h heat-inactivated guinea-pig serum and anti-HeLa immunoglobulin G stimulated [(32)P]phosphate incorporation to the same extent as heat-inactivated complement and immunoglobulin G from unimmunized rabbits. 3. Compared with cells exposed to immunoglobulin G from unimmunized rabbits together with complement, anti-HeLa immunoglobulin G with complement increased the phospholipid content of HeLa cells twofold within 5h of incubation. 4. Exposure of HeLa cells to anti-HeLa immunoglobulin G and complement for 5-22h resulted in a twofold increase in the net accumulation of [(32)P]phosphate in sphingomyelin and phosphatidylcholine and a 50% increase in the net accumulation of [(32)P]phosphate in phosphatidylethanolamine, compared with cultures exposed to immunoglobulin G from unimmunized rabbits and complement. 5. A transient accumulation of (32)P-labelled lysophosphoglycerides in HeLa cells exposed to antibody and complement was detected, confirming previous findings (Güttler & Clausen, 1969b). 6. The stimulation of [(32)P]phosphate turnover occurred in cells filling up their cytoplasma with vacuoles. This supports the suggestion that the accumulation of phospholipid in these cells may be concerned with the synthesis and function of cytomembranes.

Animals↗
PubMed2002

Tailoring anti-complement therapeutics.

Complement is a core component of the immune system, which performs vital roles in immune surveillance. However, the active products that enable complement to perform its physiological roles can inappropriately target self tissues and cause pathology. Complement-mediated inflammation and tissue destruction is an important drive to pathology in diseases as diverse as rheumatoid arthritis and dementia. Two decades ago there were no agents that could be used therapeutically to inhibit the activation of complement, but increased understanding of the natural control of complement in vivo has markedly changed this situation. The realization that drugs mimicking the action of the complement regulatory proteins present on self cells, and in plasma, could effectively control pathological activation of complement has opened the door to the use of anticomplement therapy in disease. Here we will review the development of anticomplement therapeutics from the first generation agents, which are unmodified recombinant forms of natural regulators, to recent strategies for making better drugs. We will describe strategies for targeting the anticomplement activity to the site of disease, and for extending the plasma half-life of the agent. Finally, we will illustrate a novel approach to the delivery of anticomplement agents, making prodrugs that are activated only at disease sites thus minimizing the deleterious effects of systemic complement inhibition.

Animals↗
PubMed1996

Complement-dependent cytotoxic antibodies to human T lymphotropic virus type I (HTLV-I)-infected cells in the sera of HTLV-I-infected individuals.

To investigate whether HTLV-I induces the development of complement-dependent cytotoxic antibodies in humans, sera of asymptomatic HTLV-I carriers and of patients suffering from tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) or adult T cell leukaemia (ATL) were used in a cytotoxicity assay against a panel of target cells. This panel included uninfected cell lines (CEM, Jurkat, Molt and H9), cell lines chronically infected with HTLV-I (MT2, MT4, C9IPL and HUT102), as well as lines H36 (H9 infected with HTLV-I), H9-IIIB (H9 infected with HIVms) and H9-MN (H9 infected with HIMVMN). HTLV-I+ sera induced lysis of H36 and of lines expressing HTLV-I antigens in the presence of rabbit complement, but did not lyse cells in presence of human complement. The HTLV-I+ sera also failed to lyse the HTLV-I- lines and H9 cells, suggesting that lysis was specific for HTLV-I. H36 cell lysis was prevented by IgG depletion of the sera and by dialysis of rabbit complement against EGTA or EDTA. Rabbit complement-dependent cytotoxic antibodies were present in the sera of 14/14 HTLV-I-infected individuals; the highest titres were predominantly found in the sera of the TSP/HAM patients. Such antibodies were also detected in 5/5 individuals coinfected with HIV-1 and HTLV-I, although no cytotoxic antibody could be found against HIV-infected cells. Vice versa, sera of HIV-1-infected individuals did not exert a lytic effect in the presence of complement (of human or rabbit origin) against HIV-1- or HTLV-I-infected cells. Incubation of the sera of four HTLV-I-infected patients with HTLV-I env-specific synthetic peptides demonstrated that some of the complement-dependent cytotoxic antibodies recognized epitopes located on gp46 between amino acids 190 and 209. There is no correlation of rabbit complement-dependent cytotoxic HTLV-I antibodies with the development of disease.

Antibodies, Viral↗
PubMed1998

Protection against meningococcal serogroup ACYW disease in complement-deficient individuals vaccinated with the tetravalent meningococcal capsular polysaccharide vaccine.

Individuals with properdin, C3 or late complement component deficiency (LCCD) frequently develop meningococcal disease. Vaccination of these persons has been recommended, although reports on efficacy are scarce and not conclusive. We immunized 53 complement-deficient persons, of whom 19 had properdin deficiency, seven a C3 deficiency syndrome and 27 had LCCD with the tetravalent (ACYW) meningococcal capsular polysaccharide vaccine. Serological studies were performed in 43 of them. As controls 25 non-complement-deficient relatives of the complement-deficient vaccinees and 21 healthy non-related controls were vaccinated. Post-vaccination, complement-deficient individuals and controls developed a significant immunoglobulin-specific antibody response to capsular polysaccharides group A, C, Y, W135, but a great individual variation was noticed. Also, the proportion of vaccinees of the various vaccinated groups with a significant increase in bactericidal titre (assayed with heterologous complement) was similar. Opsonization of meningococci A and W135 with sera of the 20 LCCD individuals yielded in 11 (55%) and eight (40%) sera a significant increase of phagocytic activity after vaccination, respectively. Despite vaccination, four complement-deficient patients experienced six episodes of meningococcal disease in the 6 years post-vaccination. Four episodes were due to serogroup B, not included in the vaccine. Despite good response to serogroup Y upon vaccination, disease due to serogroup Y occurred in two C8beta-deficient patients, 3.5 and 5 years post-vaccination. These results support the recommendation to vaccinate complement-deficient individuals and to revaccinate them every 3 years.

Adolescent↗
PubMed2003

Complement mediates nephrin redistribution and actin dissociation in experimental membranous nephropathy.

BACKGROUND: The onset of proteinuria in passive Heymann nephritis, (PHN), a rat model of human membranous nephropathy (MN), is complement-dependent and is associated with altered podocyte slit diaphragm integrity and dissociation of nephrin from the actin cytoskeleton. These studies examined if complement is responsible for these podocyte changes. METHODS: PHN was induced with sheep anti-Fx1A. Controls were injected with normal sheep globulin. A third group was injected with anti-Fx1A and depleted of complement with cobra venom factor. Four days later, proteinuria was measured, slit diaphragm integrity was examined by electron microscopy, nephrin distribution was studied by immunofluorescence, and the glomerular content of nephrin and its association with actin were assessed by sequential extraction of isolated glomeruli and Western blotting. RESULTS: Four days after immunization, seven out of eight PHN rats were proteinuric, whereas none of the complement depleted group had proteinuria despite similar levels of antibody deposition. Complement depletion preserved slit diaphragm morphology. Immunofluorescence microscopy with an antibody to the extracellular domain of nephrin showed a normal staining pattern in the rats depleted of complement and a shift to a more dispersed and clustered pattern in the PHN group. Western blot analysis of the glomerular extracts showed a significant reduction in the total amount of nephrin and in the fraction of actin-associated nephrin in the PHN group, whereas the amounts in the complement-depleted rats were similar to normal controls. CONCLUSION: The onset of proteinuria in the PHN model of MN is coincident with complement-dependent alterations in the association of nephrin with the actin cytoskeleton and loss of podocyte slit diaphragm integrity.

Actins↗
PubMed1977

Interactions of C-reactive protein and complement with liposomes.

Interactions between C-reactive protein (CRP) and liposomal model membranes containing phosphatidylcholine were investigated. These interactions, in the presence of human serum, resulted in consumption of each of the components of the classical complement pathway (C1-C9) and also resulted in complement-dependent damage and release of trapped glucose from certain types of liposomes. CRP-initiated lysis of liposomes was strongly dependent upon membrane lipid composition. Optimal activity occurred with positively charged liposomes containing galactosylceramide (galactocerebroside); positively charged liposomes lacking galactocerebroside released much less glucose, while negatively charged liposomes, either with or without galactocerebroside, did not release glucose at all. Glucose release was inhibited by free phosphocholine. Lesser, but significant, "background" glucose release independent of the presence of CRP also was observed with positively charged liposomes containing galactocerebroside, and this was associated with marked preferential consumption of the later-acting complement components (C3-C9). C2-deficient human serum failed to support CRP-dependent glucose release, but glucose release was observed upon reconstitution of the serum with C2. Guinea pig complement also did not support CRP-mediated glucose release, but upon addition of human C1q substantial glucose release was observed. We conclude that (i) CRP can sensitize appropriate liposomes for complement-dependent damage via the primary complement pathway starting at the level of C1q; (ii) of those studied, liposomes that are most susceptible to membrane damage contain phosphatidylcholine, have a positive charge, and contain a ceramide glycolipid; and (iii) such liposomes also are sensitive, although to a much lesser degree, to complement-dependent lysis initiated in the absence of CRP and involving consumption of terminal in excess of early acting complement components.

C-Reactive Protein↗