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PubMed1998

The complement-activating capacity of maternal IgG antibodies to blood group A in paired mother/child serum samples.

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate whether IgG antibodies to blood group A bind or activate complement after crossing the placenta. MATERIALS AND METHODS: IgG anti-A concentrations as well as C1-q-binding and the capacity of anti-A to form the C5b-9 membrane attack complex were measured in sera of 61 mother/child pairs. The enzyme-linked immunosorbent assay was used to quantitate anti-A or anti-B in maternal and neonatal serum samples. RESULTS: The concentrations of IgG anti-A in ABO-identical and ABO-compatible children born to type O or B mothers correlated significantly with maternal concentrations (p < 0.05), whereas type A or AB children had strikingly diminished concentrations of IgG anti-A. The IgG anti-A concentrations were analyzed in two different groups: first, 44 mother/child pairs with mothers and children group O or B (group I), and second, 17 pairs with mothers group O or B and children group A or AB (group II). In group I, identical or compatible pairs with regard to IgG anti-A, a significant correlation was found by Spearman's rank analysis, whereas the same analysis revealed no significant correlation in group II. The capacity of anti-A to activate complement was also more marked in newborns who were ABO-identical or ABO-compatible with their mothers, and this capacity was virtually absent in cord blood samples from incompatible babies. CONCLUSIONS: Tests for complement-dependent or complement-independent ABO blood group antibodies must be interpreted in the light of the blood group of the child.

ABO Blood-Group System↗
PubMed1990

Scleral fibroblasts. Human leukocyte antigen expression and complement production.

The authors investigated the ability of recombinant human gamma-interferon (rhIFN-gamma) to influence production of complement and expression of human leukocyte antigens (HLA) by human scleral fibroblasts in culture. Cell cultures were established by explanting sclera from normal human donor eyes. To study complement production, fibroblasts were treated with 500 units/ml rhIFN-gamma in cell culture, and media were tested for complement components by hemolytic assay after 0, 1, 3, 6, 9, and 11 days. To induce Class II HLAs, fibroblasts were exposed to rhIFN-gamma at concentrations ranging from 10-500 units/ml and incubated for 1, 3, and 6 days. The HLAs were detected by immunofluorescence in conjunction with flow cytometry. Class I antigen was detected using a monoclonal antibody directed against beta 2-microglobulin. Class II histocompatibility antigens were identified using monoclonal antibodies specific for HLA-DR, -DP, and -DQ. Although complement component C1 was produced constitutively in cell culture, the addition of rhIFN-gamma resulted in an increase in production. Complement components C2 and C4 were detected only after treatment with rhIFN-gamma. Complement production was completely inhibited by cycloheximide, and C3, C5, C6, and C7 were not present in cell culture media with or without rhIFN-gamma. Class I antigen was present on all cells before induction, and an increase in expression was noted after exposure to rhIFN-gamma. Class II antigens were absent before induction with rhIFN-gamma. After treatment with rhIFN-gamma, scleral fibroblasts expressed HLA-DR, -DP, and -DQ in a dose-dependent, time-related fashion. These findings suggest that rhIFN-gamma has multiple effects on scleral fibroblasts: (1) increased production of C1, (2) production of C2 and C4, (3) up-regulation of Class I antigen expression, and (4) expression of Class II antigens. They also suggest that scleral fibroblasts have the potential to participate in immunologic diseases of the eye.

Adult↗
PubMed1993

Killing of Trichomonas vaginalis by complement-mediated lysis is not associated with the presence of Trichomonas vaginalis virus.

We have examined the possible relationship between trichomonad killing by human serum and the presence of virus-encoded double-stranded ribonucleic acid in T. vaginalis (TVV). Indirect immunofluorescence assay revealed that non-immune serum (NIS) and T. vaginalis-immune serum (TVIS) had immunoglobulin G (IgG) antibody titres of 1:8 and 1:256, respectively, against T. vaginalis. Among the 12 isolates of T. vaginalis examined, 9 were infected with TVV. Upon long-term (> 9 months) culture, of the 9 infected isolates, 3 isolates lost the virus during the passage process. Five of 9 TVV-infected isolates were completely killed by 10% NIS while the other 4 TVV-infected isolates had viability over the range 22-81%. Three fresh non-TVV-infected isolates had viability over the range 12-89%. On the other hand, no trichomonads survived in the presence of 10% TVIS. Viability of the virus-lost isolates during long-term culture was not altered when compared with that of their corresponding fresh isolates. Heat-inactivated-NIS and -TVIS had no killing effect on trichomonads while absorbed-NIS and -TVIS (ATVIS) had a similar killing effect to NIS. Further studies on the role of antibody and complement in the killing of trichomonads by serum revealed no significant difference in trichomonad viability between treatments of Mg2+-ethylene glycol-bis-(beta-aminoethyl ether)- N,N,N1,N1- tetraacetic acid (Mg(2+)-EGTA)-TVIS and of Mg(2+)-EGTA-ATVIS. Zymosan-treated ATVIS did not kill trichomonads but zymosan-treated TVIS had a marked killing effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

In vitro studies regarding the feasibility of bovine erythrocyte xenotransfusion.

Pigs are considered the most likely source of organs and tissues should the barriers to xenotransplantation be overcome. The use of animal blood for transfusion, xenotransfusion, would have advantages over blood from random human donors with respect to supply and infection control. Large animals such as cows would be more suitable than pigs for blood donation because of easier venous access and large volume phlebotomy. Blood from 12 Holstein cows was typed and then tested for hemagglutination assay (HA), complement mediated lysis (CML), human IgM and IgG antibody binding, anti-human globulin augmented clinical cross-match and osmotic fragility with normal human serum. Results were compared with porcine erythrocytes (pRBC) and with human type O controls (hRBC). The frequency of ultra-low xenoantigen expressors was tested in a larger herd of various breeds using HA and CML. Median HA and CML titers were one of six (no HA-one of 64) and one of 26 (no CML-one of 64), respectively for bovine erythrocytes (bRBC). Hemagglutination titer was significantly higher for pRBC at one of 170 (one of four-one of 1024). HA and CML were lowest with bovine blood group J. Repeated HA and CML were negative with bRBC from one cow that also tested negative by anti-human globulin augmented cross-match with seven of nine random human sera representing the different blood groups. However, flow cytometry showed that bRBC from all cows bound human IgM and IgG. IgM mean channel fluorescence (MCF) was positively correlated with HA titer. The mean corpuscular fragility of pRBC, bRBC, and hRBC was 0.56, 0.48 and 0.41%, respectively. The frequency of HA-negative and CML-negative cows were 20 and 35%, respectively in herds of 49 animals. Bovine RBC elicit variable in vitro responses from human serum but these are uniformly much less than those seen with pRBC. Bovine RBC is more robust than pRBC. These characteristics including the potential ease and volume of blood collection make the cow a more suitable blood donor than the pig.

ABO Blood-Group System↗
PubMed1989

The clinical significance of iC3b neoantigen expression in plasma from patients with systemic lupus erythematosus.

We studied the expression of an iC3b neoantigen (iC3b-NEO) in plasma from patients with systemic lupus erythematosus (SLE), by using a monoclonal antibody specific for iC3b/C3dg/C3d, to investigate the activation of the third component of complement in SLE. The plasma iC3b-NEO level in 40 untreated patients with active SLE was significantly higher than that in 36 normal subjects (mean +/- SD 31.5 +/- 13.9 micrograms/ml versus 12.3 +/- 3.3 micrograms/ml; P less than 0.001). The plasma iC3b-NEO level was highly correlated with clinical disease activity (tau = 0.62, P less than 0.0001), and it was the parameter most closely correlated with renal histologic activity in lupus nephritis (tau = 0.52, P less than 0.0001). Also, patients with diffuse proliferative lupus nephritis had the highest levels of plasma iC3b-NEO among all World Health Organization classes of lupus nephritis (P less than 0.01). We conclude that the plasma iC3b-NEO level is strongly associated with clinical disease activity and renal histologic activity in patients with SLE, and that plasma iC3b-NEO may be a sensitive and useful measure of complement activation in SLE.

Antibodies, Monoclonal↗
PubMed1992

Activation of the alternative complement pathway accompanies disease flares in systemic lupus erythematosus during pregnancy.

OBJECTIVE: To assess the activity of systemic lupus erythematosus (SLE) during pregnancy and to distinguish it from preeclampsia. METHODS: We prospectively measured the complement activation products Ba, Bb, SC5b-9, and C4d, as well as the conventional complement determinants C3, C4, and CH50, during pregnancy in 14 patients with SLE and 10 women with preeclampsia. RESULTS: Four of the 14 SLE patients were considered to have disease flares, 3 occurring in the second trimester and 1 postpartum. In these patients, significant abnormalities of Ba, Bb, SC5b-9, and CH50 were noted. In contrast, measures of C4d did not distinguish between pregnant patients who had flares and those whose SLE remained stable. Although decreased values of C3 were rarely seen in the patients with stable disease, normal values of C3 during lupus pregnancy were not reliably associated with stable disease. Three of 10 non-SLE patients with preeclampsia had elevated levels of Ba; however, in each case, the CH50 level was close to or within the normal range. This was in sharp contrast to the findings observed in the 4 patients with active SLE, in whom high levels of plasma Ba were always associated with low CH50 values. Moreover, the ratio of CH50 to Ba was significantly lower in the patients with lupus flares than in the non-SLE patients with preeclampsia. CONCLUSION: While a decline in the CH50 level alone could otherwise be attributed to decreased synthesis of complement components, these data demonstrate that ongoing activation of the alternative complement pathway can accompany disease flares in pregnant women with SLE.

Complement Activation↗
PubMed1995

Decay-accelerating factor protects human trophoblast from complement-mediated attack.

Approximately one-fifth of first trimester losses can be characterized by the onset of hypocomplementemia prior to ultrasonographic loss of embryonic viability. Monoclonal antibodies to the membrane complement regulatory protein, decay-accelerating factor (DAF), were bound to the surface of trophoblastic tissues, with the estimated number of DAF molecules in tissues obtained from hypocomplementemic women less than those from normocomplementemic women (approximately 10%). While trophoblastic tissue obtained from normocomplementemic women did not decomplement normal human sera, pretreatment of this tissue with anti-DAF antibodies resulted in activation of the complement (C') system via the alternate C' pathway (ACP). If trophoblastic tissue from normocomplementemic women was pretreated with phospholipase C, decomplementation of human serum occurred. These data strongly suggest that trophoblasts evade the ACP with functional DAF, possibly through absorption of the molecule's lipophilic diacylglycerol membrane-anchored moiety into the outer lipid bilayer of the trophoblast and may be a rational means for the utilization of immunotherapy in recurrent spontaneous aborters.

Abortion, Habitual↗
PubMed1996

Inhibition of classical complement activation by sera from HIV-1-positive patients.

It was shown that gp120/160-coupled CD4+ T cells could be lysed by complement activation, but the target cell lysis was strongly inhibited by the majority of HIV-1-positive sera. Significantly more sera from HIV-1-infected patients with CD4+ T cell count higher than 500 microl (N = 38) as well as from patients with 200-500/microl (N = 32) showed strong inhibition of complement activation as compared to sera from those with less than 200 CD4+ T cells/microl (N = 28) (P = 0.0064 and 0.0012, respectively). Consequently, highly significant correlation between CDL inhibitory activity and CD4+ T cell count in HIV-1-infected patients was found by Spearman's rank order analysis (R = 0.399, P < 0.001). CH50 titer and functional C1-inhibitor level were significantly lower in inhibitory as compared to the noninhibitory sera (P < 0.001) and to controls (P < 0.001). The C3 activation products-C3-circulating immune complexes were not increased in inhibitory sera (P = 0.014) suggesting that inhibition of complement activation occurred at or before C3 activation level. C4d fragments and antigenic C1-INH concentration were significantly increased in both categories of HIV-1-positive sera, P < 0.001. These findings indicate that persistent and massive stimulation of complement system with HIV-1 envelope glycoproteins during all stages of the disease induced impairment of classical pathway activation by an inhibitory factor in a majority of patients, which might contribute to the onset of opportunistic infections and AIDS.

Complement Activation↗
PubMed1997

Beta-amyloid peptides initiate the complement cascade without producing a comparable effect on the terminal pathway in vitro.

Activation of the classical complement cascade by beta-amyloid peptides has been hypothesized to underlie the neurodegeneration observed in Alzheimer's diseased brains. In this study, various lots of synthetic beta-amyloid peptides, A beta(1-40), A beta(1-42), and A beta(25-35), were tested for their ability to activate both early complement cascade events and formation of the membrane attack complex through terminal pathway activation. Unlike recent reports which did not assess activation of complement terminal pathway, we found that concentrations of beta-amyloid which activated early cascade events, to an extent comparable to aggregated IgG, failed to elicit formation of comparable levels of membrane attack complex.

Amyloid beta-Peptides↗
PubMed2003

The effect of dietary intake of vitamins C and E on the stress response of gilthead seabream (Sparus aurata L.).

High dietary doses of the antioxidant vitamins C and E were administered to gilthead seabream (Sparus aurata L.) in an attempt to reduce the stress response in specimens exposed to a multiple stress situation. Fish were fed four different diets for 6 weeks: a commercial feed containing 0.1g vitamin C and 0.1g vitamin E kg(-1) acted as control diet, while experimental diets consisted of the same feed supplemented with 3g vitamin C kg(-1), 1.2g vitamin E kg(-1) or both 3g vitamin C and 1.2g vitamin E kg(-1). After 2, 4 and 6 weeks fish were exposed to stressors typical of aquacultural practices, and serum cortisol levels, complement activity (measured by the alternative pathway), blood glucose level and respiratory burst activity of head-kidney leucocytes were evaluated. The results showed that all stress-induced increases in blood glucose concentration were lower in fish fed the vitamin C and/or E-supplemented diet than in fish fed the control diet after 2 weeks of treatment, although no other differences were found at the rest of the times. Cortisol levels increased in stressed fish and did not suffer depletion as a consequence of administering vitamins C and/or E as a supplement. The natural haemolytic complement activity was not affected by the stressors but enhanced in specimens fed vitamin-supplemented diets at week 6. The respiratory burst activity was depressed by the stressors in fish fed the control diet, although only after 6 weeks of treatment were the differences statistically significant. These results suggest that vitamins C and E are involved in the hypothalamic-sympathetic-chromaffin cell axis and also interfere in tertiary stress responses such as immunodepression, where they protect the leucocyte functions.

Administration, Oral↗
PubMed1999

The effect of canine macrophages on the adherence and growth of Blastomyces dermatitidis yeast: evidence of a soluble factor that enhances the growth of B. dermatitidis yeast.

Blastomycosis is a medically important systemic fungal infection of dogs and humans. Phagocytic cells are the first line of cellular defence against B. dermatitidis, and are a prominent feature in the lesions and exudate of canine blastomycosis. The adherence of B. dermatitidis yeast to canine phagocytes, and the effects of such adherence on the growth of B. dermatitidis yeast, has not been previously reported. The results of this study demonstrate that canine complement enhances the adherence of B. dermatitidis yeast to canine macrophages. Initiation of the canine complement cascade by B. dermatitidis yeast appeared to occur predominantly by the classical pathway. Adherence of B. dermatitidis yeast to canine macrophages enhanced the growth of the yeast. In the absence of macrophages, this effect could be duplicated by incubating yeast in conditioned medium from co-cultures of macrophages and yeast. This observation suggests that a soluble factor is involved in the growth enhancement of the yeast, These findings provide new insights into the adherence of B. dermatitidis yeast to canine macrophages, and how adherence influences the proliferation of B. dermatitidis yeast.

Animals↗
PubMed1996

Chronological changes in the complement system in sepsis.

The time courses of serum complement levels and the severity of sepsis were compared in two groups of septic patients, one in which the patients survived (surviving group) and one in which they did not (nonsurviving group). The components of the complement system, namely, C3a, C4a, C5a, CH50, C3, C4, and C5, were measured at several points in time after the diagnosis of sepsis had been established. A 2-antibody radioimmunoassay was used to measure C3a, C4a, and C5a; the latex agglutination test was used to measure C3 and C4; nephelometry was used to measure C5; and Meyer's 50% hemolysis method was used to measure CH50. Following the diagnosis of sepsis, the levels of CH50, C3, and C4 were significantly lower in the nonsurviving than the surviving group, while the levels of C3a and C4a were significantly higher in the nonsurviving than the surviving group. The C5a levels were significantly higher in the nonsurviving than the surviving group, although no significant intergroup differences were subsequently noted. These results suggest that the serum levels of C3a, C4a, C5a, CH50, C3, and C4 could serve as indices of the severity of sepsis. Thus, monitoring the complement system may be useful for predicting the outcome of patients with sepsis.

Adult↗
PubMed1991

Defective activation of the alternative pathway of complement in patients with homozygous C2 deficiency: studies in two unrelated families.

Selective homozygous deficiency of the second component of complement, C2, with increased susceptibility to infection was detected in five children of two unrelated families. Because the haemolytic activity of the alternative complement pathway (AP) was in the low normal range, we evaluated the AP activation pattern. Serum levels of factor B measured immunochemically and the haemolytic function of factor B were low normal. Levels of C3d were not increased. Activation products of factor B were undetectable indicating the absence of in vivo activation of AP. Activation of C3 in vitro by activators of the AP (zymosan A and lipopolysaccharide) was profoundly deficient in homozygous C2 deficiency while heterozygous carriers exhibited intermediate values. There was no correlation between serum levels of factor B and in vitro C3 activation. We conclude that defective AP activation may contribute to increased susceptibility to bacterial infections in some patients with homozygous C2 deficiency.

Child↗
PubMed2006

Modulation of complement activity in vitro and in vivo by Yersinia wild and mutant strains.

The ability of released proteins (Yops) and surface lipopolysaccharides (LPS) from the wild-type strain Yersinia enterocolitica 8081-L2, serotype 0:8 to influence the complement activity was determined. Yops and LPS from wild-type and mutant strains showed different ability to affect the classical pathway (CP) functional complement activity in vitro. The serum CP activity was inhibited during the infection induced with six Y. enterocolitica and three Y. pseudotuberculosis strains in rabbits. The changed complement activity might be of importance for the course of Yersinia infections.

Animals↗
PubMed1999

In vitro anticomplementary activity of hederagenin saponins isolated from roots of Dipsacus asper.

Anticomplementary activity of hederagenin and related saponins isolated from Dipsacus asper was investigated in vitro. HN saponin F (3) was most potent with IC50 value of 3.7x10(-5) M followed by 3-O-beta-D-glucopyranosyl-(1->3)-alpha-L-rhamnopyranosyl-(1->2)-beta-L-+ ++arabi nopyranosyl hederagenin 28-O-beta-D-glucopyranosyl-(1->6)-beta-D-glucopyrano side (8), 3-O-beta-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl-(1->6)-beta-D-glucopyranoside (5), dipsacus saponin A (4), and hederagenin (1) on the classical pathway (CP) of complement system, while the saponins 3-5 did not show the inhibition of hemolysis and rather increase the hemolysis on the alternative pathway (AP). However, all of C-3 monodesmosides [prosapogenin CP (2), dipsacus saponin B (6), and dipsacus saponin C (7)] evoked hemolysis directly on the erythrocytes.

Animals↗
PubMed2004

Molecular cloning and sequencing of porcine C5 gene and its association with immunological traits.

The complement system helps in the lysis of invading pathogens and modulates the inflammatory as well as the humoral and cellular immune responses. C5 mediates many potent inflammatory and cytolytic events after proteolytic activation by complement convertase enzymes. Hence, to investigate the role of pig C5 ( pC5) as a candidate gene for disease resistance in pigs, the complete cDNA of pC5 was sequenced, screened for single nucleotide polymorphisms (SNPs), and an association analysis with various immunological parameters measured in F2 animals of a pig resource population based on a cross of Duroc and Berlin miniature pigs (DUMI) was carried out. In total, 5,422 bp of pC5 cDNA was sequenced, which codes for the 1,677-amino-acid precursor of C5. Four polymorphic sites were detected, one of which was segregating in the DUMI population in three genotypic patterns: AA, AC and CC. Classical (CH50) and alternative (AH50) complement activities, C3c levels, haptoglobin (HP) acute phase protein levels, and antibody titers against Mycoplasma (Mk) and Aujesky (ADV) vaccines were measured in the resource population. Association analysis between C5 and the immunological parameters was carried out using repeated measures mixed and general linear model analysis. The homozygote AA was found to be significantly different from the other two genotypes with respect to AH50 and CH50, whereas genotype CC was found to be significantly different from the other genotypes for C3c and HP levels. No significant difference could be seen between genotypes for antibody titers against vaccinations. Association of C5 with complement activity traits and acute phase proteins promotes pC5 as a candidate gene for innate disease resistance.

Acute-Phase Proteins↗