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PubMed1981

Activation of the alternative complement pathway by Trichomonas vaginalis.

The mechanism underlying the lysis of Trichomonas vaginalis by normal human or guinea pig serum was investigated. The involvement of the complement system was demonstrated by the failure of human serum deficient in C3 or C8 to mediate parasite killing and by the ablation of lytic activity observed when fresh sera were heated at 56 degrees C or treated with ethylenediaminetetraacetate. Fixation of human C3 on the parasite surface was demonstrated by indirect immunofluorescence. The involvement of the alternative complement pathway was demonstrated (i) by the inability of properdin-depleted human serum to lyse T. vaginalis and (ii) by the normal killing observed with guinea pig serum lacking C4 and with normal human or guinea pig serum treated with ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid and Mg2+ to selectively inhibit the classical pathway.

Animals↗
PubMed1989

Activation and binding of opsonic fragments of C3 on encapsulated Cryptococcus neoformans by using an alternative complement pathway reconstituted from six isolated proteins.

Encapsulated Cryptococcus neoformans yeast cells are potent activators of the complement system. We examined the interaction of the yeast cells with an alternative complement pathway reconstituted from isolated factor D, factor B, factor H, factor I, C3, and properdin. Incubation of encapsulated cryptococci with the reconstituted pathway led to activation and binding of C3 fragments to the yeast cells that was quantitatively and qualitatively identical to that observed with normal human serum. Incubation with either normal serum or a mixture of isolated proteins led to binding of 4 x 10(7) to 5 x 10(7) C3 molecules to the yeast cells. The kinetics for activation and binding of C3 were identical, with maximum binding observed after a 20-min incubation. Immunoglobulin G was not needed for optimal activation kinetics. C3 fragments eluted from the yeast cells by treatment with hydroxylamine and subsequent analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the presence primarily of iC3b on yeast cells incubated with either normal serum or the reconstituted pathway. Ultrastructural examination of the opsonized yeast cells showed that the cryptococcal capsule was the site for binding of C3 activated from normal serum or the reconstituted pathway, with a dense accumulation of C3 at the periphery of the capsule. Thus, incubation of encapsulated cryptococci in the reconstituted pathway led to deposition of opsonic complement fragments at a site that was appropriate for interaction with phagocyte receptors. Cryptococci opsonized with the reconstituted pathway showed a markedly enhanced interaction with cultured human monocytes compared with unopsonized yeast cells, indicating that the alternative pathway alone is opsonic for yeast cells. However, the results indicate that additional serum factors are needed for optimal opsonization of yeast cells because a 35% reduction in the number of cryptococci bound to macrophages was observed with cryptococci opsonized with the reconstituted pathway compared with that observed when yeast cells were opsonized with normal serum.

Complement Activation↗
PubMed1976

Immunoglobulin and complement deposition in skin of rheumatoid arthritis and systemic lupus erythematosus patients.

Rheumatoid arthritis (RA) was differentiated from systemic lupus erythematosus (SLE) by direct immunofluorescent techniques on skin specimens, using monospecific antisera for IgG, IgM, C3, C1q, properdin, and fibrin. Of 30 patients with RA studied, 20 had dermal vessel deposits of immunoglobulins and complement components in unaffected skin without the characteristic dermal-epidermal junctional fluorescence of SLE. Of 24 SLE patients studied, 24 had granular deposits of immunoglobulins and complement components in unaffected skin at the dermal-epidermal junction.

Arthritis, Rheumatoid↗
PubMed1977

Cryoglobulinaemia in Henoch-Schönlein purpura.

Sera from patients with Henoch-Schönlein purpura were examined for cryoglobulinaemia. Thirty patients had acute Henoch-Schönlein purpura, with or without renal diseas; 14 had chronic nephritis after a previous episode of purpura; and 17 were well, without urinary abnormalities, after recovering from Henoch-Schönlen purpura. Raised concentrations of cryoglobulins were present in 14 (47%) of those with acute purpura, nine (64%) of those with chronic nephritis, but none of those who had recovered completely from Henoch-Schönlein purpura. This suggests that acute Henoch-Schönlein purpura and the chronic nephritis that sometimes follows it have an immune-complex pathogenesis. IgA and properdin were found in several cryoglobulins, which suggested that complement had been activated via the alternative pathway, but isolated cryoglobulins capable of splitting C3 in vitro did so via the classical pathway.

Adolescent↗
PubMed1977

Serum complement changes in W/Fu rats inoculated with syngeneic (C58NT) D lymphoma cells.

Weanling W/Fu rats were inoculated intraperitoneally with 1 X 10(6) to 1 X 10(7) (C58NT)D Gross virus-induced lymphoma cells. Sera obtained 7 days later showed moderate to marked depressions of overall hemolytic activity, C1, C3 and properdin. These changes were not observed in uninjected W/Fu rats or in animals inoculated with syngeneic normal spleen cells. In the latter group and in the tumor-bearing animals, factor B levels were also depressed. Evidence of complement utilization was also observed in the ascitic fluids of the tumor-bearing W/Fu rats.

AKR murine leukemia virus↗
PubMed1992

Assay for opsonin activity based on chemiluminescence of a Cypiridina luciferin analog.

Opsonin activity (OA) was investigated in serum samples from cord blood of 11 full-term newborn infants and 12 healthy adult volunteers by the method of luminol-dependent chemiluminescence (L-CL) and Cypiridina luciferin analog-dependent chemiluminescence (CLA-CL) together with the measurement of complement components (C3, C4, C3A and properdin). CL and complement components of cord samples were significantly lower than that of healthy adult blood. CLA-CL showed a significant correlationship to C3 and C3A. L-CL also displayed a significant correlationship to C3A but the relationship to C3 was not significant. From these results, when OA is measured by CL, CLA-CL is preferred to L-CL as a technique.

Adult↗
PubMed1974

Glomerular complement components in human glomerulonephritis.

154 of 255 individual human renal biopsies studied by immunofluorescence contained varying combinations of immunoglobulins (Ig), complement (C) components C1q, C3, C4, C5, C6, C8, C3 proactivator (C3PA), and/or properdin. 10 patients had linear deposits of Ig in glomeruli characteristic of antiglomerular basement membrane (GBM) antibodies; nine patients had C3 deposits (minimal in three) with generally lesser amounts of C1q, C4, C5, C6, and/or C8. 118 of the patients had granular deposits of Ig, suggesting immune complex glomerulonephritis; 114 of these had deposits of C3, usually accompanied by C1q, C4, C5, and/or C6. These observations indicate that the entire C sequence is deposited in glomeruli in most Ig-mediated glomerulonephritides. However, certain cases of anti-GBM glomerulonephritis with few or no C deposits may utilize pathways of injury independent of C.21 patients had granular C3 deposits without detectable Ig. C5, C6, and C8 were present in the majority of these patients while C1q was absent and scant C4 was observed in only two patients. The presence of only late-acting C components in the absence of Ig, C1q, and C4 suggests selective, possible nonimmune activation of the alternate C pathway. Finally, five patients had granular deposits of C3, C5, C6, and/or C8 diffusely in all or most glomeruli with a lesser number of glomeruli having additional focal granular deposits of Ig, C1q, and C4. This observation suggests that at least two patterns of C activation can occur simulatenously, possibly triggered by antecedent immune complex deposition and then perpetuated by an as yet undetermined mechanism.

Adult↗
PubMed1975

Restoration by purified C3b inactivator of complement-mediated function in vivo in a patient with C3b inactivator deficiency.

In a patient with lifelong increased susceptibility to infection and multiple abnormalities in complement-mediated functions, the infusion of normal plasma had been seen to produce a prolonged partial correction of serum abnormalities. It was subsequently shown that the patient was genetically deficient in the C3b inactivator and that immunochemical depletion of C3b inactivator from normal serum resulted in abnormalities similar to those found in the patient's serum, including alternative pathway C3 activation. Highly purified C3b inactivator was obtained from the euglobulin fraction of normal human serum, sterilized by filtration, and infused intravenously. Partial or complete correction of almost all the known serum abnormalities was obtained. C3b almost disappeared from the serum within 4-5 h, as did Factor C activity. Native C3, C5, and serum hemolytic activity rose to normal or near-normal levels over 4 days and were sustained for another week. Factor B, properdin, opsonic activity, and bactericidal activity reached a level at least two-five times that found before the infusion within 24 h and fell over the next 5 days. These observations prove the primary role of C3b inactivator deficiency in the patient's disease and demonstrate clearly the curcial role in vivo of C3b inactivator in modulating alternative pathway activity.

Blood Proteins↗
PubMed1985

Formation of soluble immune complexes by complement in sera of patients with various hypocomplementemic states. Difference between inhibition of immune precipitation and solubilization.

To examine whether the ability of complement to form soluble immune complexes plays a role in preventing immune complex-mediated diseases, we analyzed the capacity of complement to inhibit immune precipitation (IIP) and to solubilize preformed immune aggregates (SOL) in 23 sera of patients with various hypocomplementemic states, and we correlated the results of these studies with the clinical syndromes found in the various patients. In sera with deficiency or depletion of early classical pathway components, IIP was profoundly altered, whereas SOL was delayed but in the normal range. In contrast, in sera with C3 depletion but intact classical pathway and in properdin-deficient serum, IIP was initially preserved, whereas SOL was abolished. Since the incidence of immune complex diseases in various hypocomplementemic states correlates with the severity of IIP defects, but not with reduced SOL, it is suggested that IIP is an essential biological function of complement that prevents the rapid formation of insoluble immune complexes in vivo.

Antigen-Antibody Complex↗
PubMed1985

Components of the alternative pathway of complement in otitis media with effusion.

An evaluation of the alternative pathway of complement was undertaken in patients with otitis media with effusion (OME). Middle ear fluid (MEF) and serum specimens were obtained from 34 patients at the time of elective myringotomy for OME. Bacterial, viral, and mycoplasma cultures were made for all specimens of the fluids. Immunochemical determinations by radial immunodiffusion were performed for C3, C5, factor B, properdin, factor H, factor I, and albumin. Each patient's recent clinical course and past history were reviewed. The results of all viral and mycoplasma cultures were negative. Three of 55 bacterial cultures were positive for type B Haemophilus influenzae. All components of the alternative pathway measured were found to be present in varying amounts in MEF. When the levels of the complement components were compared to the clinical factors studied, there were no observable differences. These data suggest that components of the alternative pathway of complement are present in OME and are not useful in predicting the clinical course or outcome of this disorder.

Adolescent↗
PubMed1977

Alternative pathway of complement in sickle cell disease.

Thirty-one patients, 10 months to 20 years of age, were studied. A complement abnormality was not identified in sera from patients with sickle cell disease (SCD) by the methods employed in the present study. Concentrations of C3, factor B, total hemolytic activity (CH50), properdin, and C3b inactivator were similar in sera from patients and control subjects (Table 1 and Fig. 2). Although concentrations of C3b inactivator protein were below normal in a few patients, there was no evidence that these levels were low enough to alter the functions mediated by this protein. Initiation of the complement sequence via the alternative pathway by reaction with inulin was equal in patient and control sera when assessed by the activation of factor B, cleavage of C3 and the comsumption of hemolytic complement components (Table 1). Lysis of erythrocytes treated with reduced glutathione was similar in patient and control sera during alternative pathway activation (Fig. 3), indicating comparable formation of lytic complexes via this pathway. An abnormality of the alternative pathway was not detected when the serum from patients with sickle cell disease was reacted with inulin. Thus, this polysaccharide, although commonly empolyed to assess alternative pathway function, is not satisfactory for studying serum from these patients. In addition, activation of the alternative pathway by cobra venom factor was comparable with controls when assessed by the lysis of glutathione-treated erythrocytes.

Adolescent↗
PubMed1984

HLA-linked complement markers in Alzheimer's and Parkinson's disease: C4 variant (C4B2) a possible marker for senile dementia of the Alzheimer type.

We determined the gene frequencies for the alleles of the HLA-linked complement markers C2, properdin factor B (BF), C4A (Rodgers) and C4B (Chido), and the red cell enzyme glyoxalase-I in 38 unrelated patients with senile dementia of the Alzheimer type, 42 patients with idiopathic Parkinson's disease, and 59 unaffected, aged-matched control blood donors. In senile dementia of the Alzheimer type and in Parkinson's disease, no significant difference was found in the gene frequencies of alleles at either the BF, C2, or GLO-I locus compared with those of age-matched controls. In senile dementia of the Alzheimer type, a striking increase in the frequency of the rare C4B locus allele, C4*B2, was apparent, resulting in the high relative risk of RR = 8.8 (p less than 0.0001) for this disorder.

Alleles↗
PubMedDate not supplied

Immune complexes and complement in serous and mucoid otitis media.

The occurrence and quantity of immune complexes in middle ear effusion (MEE) and serum, as well as serum levels of complement (C) factors were investigated in patients with chronic otitis media. Immune complexes were demonstrated in 85% of the serous MEE and in 28% of the sera. Depressed Clq values and presence of abnormal complexes, composed of subcomponents of the first C factor, indicated a disturbed function of the C system. Activation of C by the classical pathway was demonstrated in 23% of the patients. Decreased levels of properdin were also noted. The disorders within the C system tended to normalize as the otitis subsided.

Antigen-Antibody Complex↗
PubMedDate not supplied

Complement aberrations in serum from children with otitis due to S. pneumoniae or H. influenzae.

Complement components C1q, C1s, C3, C4, factor B and properdin were measured, together with C1 subcomponent complexes and Cq binding substances in acute and convalescent samples from patients with relapsing and non-relapsing otitis media due to S. pneumoniae and H. influenzae. Analysis of C1 subcomponent complexes together with the finding of low C1q levels gave evidence of a disturbed C1 function in acute OME. Furthermore, complement activation by the classical and by the alternative pathways was demonstrated. Complement aberrations were more pronounced in relapsing otitis than in non-relapsing otitis. C1q binding substances that might possibly cause the complement aberrations found were present in most of the patients.

Acute Disease↗
PubMed1989

Complement deficiencies in selected groups of patients with meningococcal disease.

We have examined 125 individuals who have earlier had meningococcal (mgc) disease. They belonged to one or more of the following groups: (1) 2 or more cases of mgc disease in the same family; (2) individuals with 2 episodes of mgc disease or with 1 episode of mgc disease and 1 or more episodes of purulent meningitis of another aetiology; and (3) infections with Neisseria meningitidis belonging to serogroups that are uncommon as causes of disease and presumably low-virulent (W-135, 29E, X, Y). Among these we found 15 complement (C)-deficient individuals (12%). The prevalence of C deficiency in the groups above was 7%, 41% and 19%, respectively. The first group (family cases), is very heterogeneous and may be further subdivided into 2 groups: families whose members fell ill within an interval of 30 days (in these the prevalence of C deficiency was 2%), and families in which the interval between mgc disease cases exceeded 30 days (in those the prevalence of C deficiency was 14%). We found a predominance of defects of the initiation pathways, with properdin deficiency being the most common.

Animals↗
PubMed2007

Decay-accelerating factor must bind both components of the complement alternative pathway C3 convertase to mediate efficient decay.

Decay-accelerating factor (DAF; CD55) inhibits the complement (C) cascade by dissociating the multimolecular C3 convertase enzymes central to amplification. We have previously demonstrated using surface plasmon resonance (Biacore International) that DAF mediates decay of the alternative pathway C3 convertase, C3bBb, but not of the inactive proenzyme, C3bB, and have shown that the major site of interaction is with the larger cleavage subunit factor B (Bb) subunit. In this study, we dissect these interactions and demonstrate that the second short consensus repeat (SCR) domain of DAF (SCR2) interacts only with Bb, whereas SCR4 interacts with C3b. Despite earlier studies that found SCR3 to be critical to DAF activity, we find that SCR3 does not directly interact with either subunit. Furthermore, we demonstrate that properdin, a positive regulator of the alternative pathway, does not directly interact with DAF. Extending from studies of binding to decay-accelerating activity, we show that truncated forms of DAF consisting of SCRs 2 and 3 bind the convertase stably via SCR2-Bb interactions but have little functional activity. In contrast, an SCR34 construct mediates decay acceleration, presumably due to SCR4-C3b interactions demonstrated above, because SCR3 alone has no binding or functional effect. We propose that DAF interacts with C3bBb through major sites in SCR2 and SCR4. Binding to Bb via SCR2 increases avidity of binding, concentrating DAF on the active convertase, whereas more transient interactions through SCR4 with C3b directly mediate decay acceleration. These data provide new insights into the mechanisms involved in C3 convertase decay by DAF.

Biological Assay↗
PubMed1976

[The mechanism of immune alteration of leukocytes].

The effect of properdin, lysozyme and complementary activity of the blood serum on the degree of immune alteration of leukocytes was revealed on the clinico-experimental material. In the leukocytolysis a neutrophil apparently serves as a mechanical substrate. It is likely that the cytophilic organic antibodies conditioned the indirect variety of leukocytolysis.

Adult↗
PubMed1976

[Indicators of nonspecific immunity in cirrhosis and primary cancer of the liver].

The study of some factors of nonspecific immunity in 85 patients with cirrhosis and in 9 patients with primary cancer of the liver revealed a decrease of all factors of nonspecific immunity under consideration, while in primary cancer of the liver--selective and more sharp fall of properdin level. The complement, as compared with the control, was not changed, whereas lysozyme was statistically reliably higher than in healthy persons.

Adult↗