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PubMed1985

Chronic glomerulonephritis with massive IgA deposits.

A total of 234 patients with chronic glomerulonephritis, detected on the basis of clinical, immunological and pathomorphological criteria, have been examined. A group of 23 chronic glomerulonephritis patients with massive deposits of immunoglobulin A found by immunofluorescent examination, has been separated on the basis of immunohistochemical studies. In this group, occurrence of different morphological forms of glomerulonephritis has been observed: 30.4% mesangial-proliferative glomerulonephritis, 13% submicroscopic glomerulonephritis and one case of membranous glomerulonephritis. Complete haemolytic activity of complement, level of complement components C3 and C4, immunological complexes circulating in blood, properdin and immunoglobulin A levels, fibrin and fibrinogen (FDP) degradation product concentrations and their 24-hour excretions with urine have been determined. Preliminary observations of this group of patients seem to indicate a positive effect of steroid therapy in glomerulonephritis with IgA deposits, irrespective of the morphological form of the disease.

Adolescent↗
PubMed1992

Complement profile in primary biliary cirrhosis.

PBC is a chronic progressive liver disease of unknown etiology. Several abnormalities found in PBC support the hypothesis that it may be considered an autoimmune disease. Despite the complex and interesting relationship that exists between autoimmune disorders and the complement system, very few reports on the level of the serum complement component in PBC have been published, and most of these comprised only a few patients or analyzed only a scant number of the complement components. In the present study, sera of 73 PBC patients were analyzed for the levels of 10 complement components. It was found that the levels of most of the serum complement components, including C1q, C2, C3, C5, C7, properdin and factor B were significantly elevated in patients with PBC in comparison to healthy controls. The level of C4 was slightly lower than that of the normal controls (p = 0.019), while the levels of C6 and C8 were within the normal range. The number of PBC patients with serum levels of C4 and C6 < 60% of normal pooled serum was higher than in the respective control groups (6/69 compared with 0/26 and 4/71 compared with 0/27, respectively). However, the difference was not statistically significant. Thus, our study shows alterations in the levels of most complement components in PBC, the reasons for which are discussed.

Autoimmune Diseases↗
PubMed2005

Complement profile in childhood immune thrombocytopenic purpura: a prospective pilot study.

Immune thrombocytopenic purpura (ITP) is a frequent, usually acute hematologic complication of viral diseases in children. Its evolution is usually benign with spontaneous resolution. Some authors have raised the hypothesis of a possible role of the complement system in the pathogenesis of ITP. In the present study, we measured the complement system components in 25 children with ITP. The complement system was abnormal in most patients with ITP as compared with the control group: 20 of the 25 patients had at least one low-component level. The most affected components were properdin, factor H (p=0.005 and p=0.001, respectively), C1q, C9, and factor B. Our results may indicate a possible role for the complement system in the pathogenesis of pediatric ITP.

Adolescent↗
PubMed1975

Hereditary complement (C2) deficiency with dermatomyositis.

A 60 year old white man in previous good health presented with a 6 month history of progressive muscle weakness. Clinical and laboratory findings were typical of dermatomyositis. Muscle biopsy confirmed the presence of inflammatory myopathy; deposits of immunoglobulin G (IgG), immunoglobulin M (IgM) or third component of complement (C3) were not detected by immunofluorescence. No evidence was found for an associated neoplasm. An unexpected finding was the total absence of serum hemolytic complement activity. Further investigation revealed that the complement defect was attributable to a selective and total absence of the second component of complement (C2), as determined by both functional and immunoprecipitin assays. Family studies indicated that the defect was inherited in an autosomal recessive manner, as has been observed in the previously reported C2-deficient kindreds. This case demonstrates that typical muscle lesions of dermatomyositis can occur in the presence of a complement defect which would preclude activation of the classic (C1-C4-C2) complement pathway. The case is of further interest as one of a series of recently reported associations of rheumatic diseases with hereditary complement deficiencies. Study of the functional properties of the propositus' C2-deficient serum demonstrated normal generation of chemotactic activity in the presence of endotoxin or aggregated IgG, and normal or near normal bactericidal activity against Salmonella typhi O 901 and Hemophilus influenzae, type b. These findings emphasize the importance of the alternate (properdin) pathway of complement activiation in these functions.

Biopsy↗
PubMed1976

Circulating immune complexes and complement sequence activation in infectious mononucleosis.

The role of immune complex formation was investigated in a patient with infectious mononucleosis complicated by an urticarial rash. Circulating cryoprotein immune complexes were identified during the urticarial phase of the illness, and disappeared during recovery. These complexes were composed of immunoglobulins G (IgG), M (IgM) and A (IgA), complement components C3, C4 and C5, Epstein-Barr (EB) virus capsid antibody and particles resembling EB virus. The IgG subtypes identified in the immune complexes were the complement fixing IgG-1, IgG-2 and IgG-3. The C3 activator of the properdin complex was detected in serum obtained during that acute phase but not after recovery. Thus, the transient appearance of circulating complement-fixing immune complexes was associated in this patient with activation of both classic and alternate complement pathways. The findings suggest that these complexes may be involved in the rash associated with infectious mononucleosis.

Adult↗
PubMed1977

Mesangial proliferative glomerulonephritis with irregular intramembranous deposits. Another variant of hypocoplementemic nephritis.

Two patients with a persistent mesangial proliferative glomerulonephritis and reduced serum C3 levels have been followed for six and 10 years. Both have had a mild course with normal renal function and spontaneous morphologic improvement. Levels of the fourth component (C4) and second component (C2) of complement, and properdin factor B have been normal; the third component (C3) of complement nephritic factor has not been detected. Ultrastructurally, irregular intramembranous electron-dense deposits are present, primarily within the lamina densa. These deposits are separated by varying lengths of normal-appearing glomerular basement membrane. Intramembranous and subendothelial electron-lucent areas, containing vesicles, are also seen. Subendothelial deposits, mesangial interposition, splitting of the glomerular basement membrane and ribbon-like intramembranous deposits are not found. The disease in these patients was clinically indistinguishable at onset from mrmbranoproliferative glomerulonephritis (MPGN). The possibility of a variant with mild clinical course, no progression and spontaneous morphologic improvement is important in planning and assessing treatment programs in this disease group.

Adolescent↗
PubMed1980

A hypocomplementemic vasculitic urticarial syndrome. Report of four new cases and definition of the disease.

We describe four new patients with a unique syndrome of persistent urticaria, with leukoclastic angiitis, severe angioedema, occasional life-threatening laryngeal edema, arthritis, arthralgia, neurologic abnormalities and pronounced persistent hypocomplementemia. The complement abnormalities involved markedly reduced levels of the Clq subunit of the first component of complement (Cl) in the presence of near normal levels of Clr and Cls subunits of Cl; modest to marked depletion of the fourth component of complement (C4), the second component of complement (C2) and the third component of complement (C3); and normal levels of the fifth through ninth components of complement (C5 through C9) and properdin factors B and D. A striking serologic abnormality found in all patients was the presence of low molecular weight (7S) proteins which precipitated with Clq in agarose gels; these previously were shown to be comprised at least in part of immunoglobulin G. The present experience is offered to help to define the clinical, histopathologic and serologic characteristics of this entity, designated hypocomplementemic vasculitic urticarial syndrome, and to emphasize its distinctiveness and prevalence.

Adult↗
PubMed1982

Noninfectious ring-shaped keratitis associated with Pseudomonas aeruginosa.

Ring-shaped keratitis appeared in the left eye of a 37-year-old woman who had worn soft contact lenses for more than five years. The corneal ring began to appear within seven days of a central corneal abrasion. Gram staining of the patient's contact lens cleaning solution showed many gram-negative rods, and microbiologic investigations of the patient's soft contact lens and contact lens case disclosed Pseudomonas aeruginosa. There was no clinical or laboratory evidence of an infectious process. Prompt treatment with polymyxin B-bacitracin ointment and prednisolone acetate 1% eyedrops led to resolution of the opacity and a return to the patient's normal visual acuity. The P. aeruginosa endotoxin may have been transferred through the epithelial break into the superficial corneal stroma, leading to ring formation via endotoxin-initiated, properdin-mediated, antibody-independent complement activation.

Administration, Topical↗
PubMed1980

Activation of the alternative pathway of complement by microcrystalline cholesterol.

Microcrystalline cholesterol in either the anhydrous or monohydrate form was a potent activator of the alternative pathway of complement as measured by the electrophoretic conversion (crossed immunoelectrophoresis) of C3 and properdin factor B. Chelation with 0.01 M ethylene-diaminetetraacetate (EDTA) completely eliminated conversion, but 0.01 M ethyleneglycol tetraacetate (EGTA) had little or no effect. The magnitude of activation by cholesterol crystals was similar to that by zymosan, heat-aggregated IgG, or crystals of monosodium urate monohydrate. The microcrystalline forms of the acetate, linoleate, or oleate esters of cholesterol did not activate more complement than did saline controls. Cholestanol retained full C3 activating potency, but cholestane had none. Binding of IgG by cholesterol monohydrate is very small compared to that by sodium urate.

Adsorption↗
PubMed1989

Deposition of complement activation products on plastic-adsorbed immunoglobulins. A simple ELISA technique for the detection of defined complement deficiencies.

The activation of complement components in human serum has been studied using immunoglobulins adsorbed to microtiter plates. The sequential deposition of complement fragments was detected by a series of mono- and polyclonal antibodies in an indirect enzyme-linked immunosorbent assay (ELISA). Antibodies against C1q, C1s, C4b/d, C3b/d, factor B, C5b-9 membrane attack complex (MAC), the regulatory complement proteins C4 binding protein (C4bp) and properdin were reactive. Several lines of evidence suggest that complement activation was via the classical pathway: (1) complement activation was highly isotype-restricted with regard to the adsorbed Igs (human IgG1 and IgG3 as well as mouse IgM, IgG2a and IgG2b isotypes are strong activators in contrast to human IgG2, IgG4, IgA and mouse IgG1); (2) Ca2+ depletion, heat treatment (56 degrees C for 45 min), incubation with 0.5 M KSCN or heat-aggregated immunoglobulins (aggIgG) abrogated serum activity; (3) complement deficient sera (C1q def', C2 def', C6 def' human sera; C2 def', C4 def' guinea pig sera) showed impaired deposition of the complement components that follow the missing component in the cascade of activation. In a clinical study sera from patients with systemic lupus erythematosus (SLE) were investigated in order to measure the effect of hypocomplementemia due to complement consumption. The results obtained suggest that this new and simple assay is well suited for (1) the detection of various inherited complement deficiencies, (2) the semiquantitative evaluation of sera with decreased complement levels, (3) a more detailed study of complement components bound to a solid phase.

Adsorption↗
PubMed1984

Search for biological/genetic markers in a long-term epidemiological and morbid risk study of affective disorders.

A long-term epidemiological genetic study was conducted in which all new patients were evaluated prospectively at the Foundation for Depression and Manic Depression and two Lithium/Affective Disorders clinics at the Columbia-Presbyterian Medical Center between the years of 1972 and 1978. All patients met Feighner, RDC and DSM III criteria for Major Depressive Disorder after initial clinical screening interviews and were further subtyped using the Fieve-Dunner 7-point criteria. All 604 probands and 90% of 2711 first-degree relatives were interviewed blindly by diagnosticians trained in the use of the SADS structured interview. Cumulative morbid risk in parents, siblings and children of 490 bipolar probands was 15.6 +/- 3% and 14.0 +/- 1.7% in the first-degree relatives of 114 unipolar probands. A number of biological and genetic marker studies were simultaneously performed on samples of the overall population. The enzymes catechol O-methyltransferase and dopamine beta-hydroxylase, and the dexamethasone suppression test (SDT) did not show any biological marker value for outpatients even though both enzymes were determined to have hereditability. The HLA system, monoamine oxidase and acetylcholinesterase segregated differently from normal controls in samples of the patient population. The positive association findings with monoamine oxidase and the HLA system conflicted with the positive findings of other investigators, leaving doubtful their biological marker value. Red cell acetylcholinesterase was found to be significantly lower in affective disorder patients than in controls. This positive association finding was recently replicated by Mathews et al. (1982) but needs further confirmation. Using 28 blood group markers, a prior association study between the trait defining susceptibility to affective disorder and the genetic marker was positive for haptoglobin GC, and properdinfactor B, confirming earlier findings. Using the sib-pair method on the remaining 25 blood groups revealed that none other than peptidase A showed significant linkage with affective disorder since one significant finding is expected by chance. We conclude from the overall morbid risk data and segregation analyses that bipolar manic-depressive illness is a spectrum disease inherited through a multifactorial mode of genetic transmission (which is not synonymous with polygenetic inheritance) with possible genetic heterogeneity and find no evidence for X-linkage. Additional studies with acetylcholinesterase, haptoglobin, GC, and properdin-factor B are needed to confirm their positive biological/genetic marker value suggested by our long-term epidemiological study.

Acetylcholinesterase↗
PubMed1993

Reduced CR1 expression on aged human erythrocytes: immuno-electron microscopic and functional analysis.

Recognition and clearance of aged human erythrocytes (AE) is a complex process involving immune and non-immune reactions. Complement activation on the surface of AE and deposition of the C3b complement component appear to facilitate this process. Complement receptor type 1 (CR1, CD35) expressed on the surface of human erythrocytes binds to C3b molecules and promotes their inactivation by complement factor I. This may protect the erythrocytes from lysis by complement and by phagocytes. It has been previously reported that aging of human erythrocytes is accompanied by a decrease in the number of CR1 molecules expressed on their surface. Results presented here further support this finding with for the first time a presentation of immune-electron microscopic observation. Haemagglutination and binding assays showed that AE express significantly fewer CR1 (CD35) molecules than young erythrocytes (YE). This is associated in AE with reduced CR1-like factor I co-factor activity and increased deposition in vivo of C3, C4 and properdin as well as increased sensitivity to lysis in vitro by homologous and heterologous complement. Three different immuno-electron microscopical techniques have been used to clearly show the quantitative difference in CR1 (CD35) expression between AE and YE. Finally our results demonstrate that the previously reported clustered arrangement of CR1 (CD35) on human erythrocytes is similar on aged and young erythrocytes.

Antibodies, Monoclonal↗
PubMed1980

In vitro effects of radiographic contrast media on the complement system.

The effect of several radiographic contrast media on the complement system in vitro was examined using quantitative crossed immunoelectrophoresis. Diatrizoate, iothalamate, metrizoate, and methiodal did not cause electrophoretic conversion of C3 or properdin factor B. In fact, the small degree of spontaneous conversion occurring when serum is incubated in polypropylene tubes was inhibited by these contrast media or by hypertonic sodium chloride. Metrizamide caused enhanced conversion of C3 and factor B that was only partially inhibited by ethylene glycol tetracetic acid (EGTA) but completely inhibited by ethylenediaminetetraacetic acid (EDTA). Iodipamide caused a unique electrophoretic alteration of C3 that was not affected by EDTA or several other inhibitors and that was not identical with the usual products of C3 activation. Iodipamide in very low concentrations inhibited complement activation through the classical pathway.

Citrates↗
PubMed1996

Complement activation by 3-mercapto-1,2-propanediol immobilized on gold surfaces.

Thiol-modified surfaces are chemically well defined and suited for surface biological model experiments and biomaterials research. 3-Mercapto-1,2-propanediol (mercaptoglycerol, MG), immobilized on gold, spontaneously binds immunoglobulins from human serum and activates the complement system. The surface-bound complement factors were detected by ellipsometry-antibody techniques. The overall complement activation was subsequently corroborated independently with enzyme immunosorbent assay (EIA) and sheep and chicken erythrocyte haemolytic complement techniques. EIA experiments indicated elevated levels of C4d, but no significant increase of factor Bb was evident in the test serum from the MG system. The haemolytic assays show that MG surfaces consume complement factors from both pathways. Ellipsometry revealed that immunoglobulin G (IgG) and complement factor 1q (C1q) are transiently antibody detectable on MG after exposure to whole serum by the use of antibody techniques. Complement factor 3 (C3), C2, C4 and properdin could be detected on the surface, but not factors H and B. The total adsorbed mass and particularly C3 antibody deposition were suppressed by using EGTA-Mg2+ serum. The results suggest that MG surfaces initially activate complement via the classical pathway. Other IgG binding surfaces also appear to behave in a similar manner.

Animals↗
PubMed1988

Activation of complement by human serum IgA, secretory IgA and IgA1 fragments.

UNLABELLED: Activation of the complement (C) system by human IgA was studied. Both subclasses of IgA, IgA1 and IgA2, and secretory IgA were shown to activate C, as determined by deposition of C3 on glutaraldehyde-activated microwells coated with IgA. The activation of the C system occurred in the presence of MgEGTA and not in D-deficient serum. In addition to C3, deposition of properdin (P) but not of C4 was detected. These results indicate that C activation, as determined by measuring deposition of C3 and P, occurred by the alternative pathway (AP). The data further show that the major part of the hinge region, which is deleted in IgA2 as compared with IgA1 and which forms the major structural difference between the two subclasses, is not involved in C activation. Reduction and alkylation destroyed the ability of IgA to activate C, as has also been demonstrated for IgG. In order to define the C activating region of the IgA molecule, several fragments of IgA1 were tested. The four-chain molecules F(ab')2 and F(abc)2 were shown to activate the AP. No activation was observed with the two-chain fragments Fab and Fc. The Fc fragment of IgA also did not activate the CP, as does the Fc fragment of IgG. This indicates that activation of the AP of C by IgA is dependent on the presence of the F(ab')2 fragment. IN CONCLUSION: human IgA does activate C by the AP. This activation requires an intact F(ab')2 fragment.

Complement Activation↗
PubMed1992

Dissociation of primary antigen-antibody bonds is essential for complement mediated solubilization of immune precipitates.

The role of dissociation of primary antigen-antibody bonds in the solubilization of immune complexes (IC) has been investigated using photo-affinity crosslinked IC comprising NAP15-BSA and murine monoclonal anti-DNP antibodies. Non-covalently linked IC were solubilized rapidly when incubated with normal human serum (NHS), whereas covalently-linked IC were solubilized poorly or not at all. The rate and extent of complement activation produced by incubating covalently-linked and non-covalently linked IC with NHS was similar as assessed by the production of the C1s:C1-inhibitor, C3:properdin and C5b-9 complexes and the anaphylatoxins C4a and C3a. Thus, the inability of serum to solubilize photo-affinity crosslinked IC must be due to failure of dissociation of primary antigen-antibody bonds.

Animals↗
PubMed1994

Inhibition of complement activation by natural sulfated polysaccharides (fucans) from brown seaweed.

In the present study, we demonstrate that natural sulfated polysaccharides (fucans) isolated from brown seaweed are potent inhibitors of human complement activation. A fucan fraction of chromatographic molecular weight 22,600, termed BS8, was found to inhibit classical and alternative pathway activation in whole serum in a dose-dependent fashion. Fucan BS8 inhibited formation of the classical pathway C3 convertase by interfering with C1 activation or by inhibiting C4 cleavage and the interaction between C4b and C2. The fucan also inhibited formation/function of the alternative pathway C3 convertase by suppressing the binding of B to C3b and by interfering with the stabilizing function of Properdin. The inhibitory effect of fucans on formation of the C3 convertases was dependent on the molecular weight of the polysaccharide for compounds of chromatographic molecular weight below 16,600. Fucan had no effect on the function of the terminal complex. Since fucans were more efficient than heparin in inhibiting activation of the classical pathway in whole serum and exhibited a lesser specific anticoagulant activity on a molar basis, our results suggest that these natural sulfated polysaccharides have a potential for use as anti-complementary and anti-inflammatory agents.

Complement Activation↗
PubMed1985

Effects of chloroquine on the serum complement system.

Chloroquine, a well-known anti-malarial and anti-inflammatory agent, was studied with respect to its effect on the serum complement system. The drug exhibited significant in vitro anti-complementary activity only at a very high non-therapeutic dose of 48 mg/ml. Chloroquine-induced in vitro complement consumption was observed to take place even in the absence of Ca2+ and Mg2+ ions. The drug also haemolyses rabbit erythrocytes in the presence of Mg2+-EGTA and immunoelectrophoretic studies of fresh human serum and chloroquine incubation mixture against specific anti-C3 and anti-factor B antisera have demonstrated that it cleaves both C3 and factor B. In another experiment, chloroquine failed to exert inhibitory effects on complement utilisation by immune complexes. Studies of the serum complement profile of Plasmodium falciparum-infected malaria patients receiving chloroquine therapy indicated that, in contrast to the situation in vitro, the serum C3 level is invariably decreased. Marginal reductions in the levels of C4, factor B and properdin were also found in some of these patients, while administration of chloroquine to normal human individuals failed to produce any significant change in their serum complement profile. It is, therefore, probable that malarial parasites and not chloroquine are responsible for complement activation in patients suffering from malaria.

Adult↗