Humoral alloreactivity in recipients of renal allografts as a risk factor for the development of delayed graft function.
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Complement C4↗
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Vascular deposition of complement-split products in kidney allografts with cell-mediated rejection.
Complement activation in 73 renal transplant biopsies was investigated by indirect immunoperoxidase staining using MoAbs reactive with complement-split products. Intense deposition of complement fragments C4d and C3d in peritubular capillaries, indicating activation of the classical pathway, could be detected in the majority of transplanted kidneys with cell-mediated rejections. Abundant deposition of complement-split products was observed in 22 early biopsies from patients with high 'immunological risk' (i.e. previous, rejected transplants and/or circulating antibodies against HLA-antigens). Despite negative results in the crossmatch before transplantation and paucity of immunoglobulins in transplant biopsies, antibodies directed against endothelial cell antigens should be considered as a possible cause of classical complement activation.
Antibodies, Monoclonal↗
Reactive oxygen product formation by human neutrophils as an early marker for biocompatibility of dialysis membranes.
Production of reactive oxygen intermediates (ROI) by neutrophils (PMN) in vivo was examined by a whole blood assay using dichlorofluorescein-diacetate (DCFH-DA) in 10 patients each dialysed consecutively with two different dialyser membranes. Haemodialysis (HD) with cuprophan membrane (CM) led to a significantly (P < 0.001) more pronounced ROI production by PMN (2.4 +/- 0.5-fold increase in intracellular oxidation of DCFH-DA) compared with HD with polysulfone membranes (PM; 1.5 +/- 0.2-fold). HD with CM induced a decrease in PMN count by about 90%, whereas PM induced a decrease by only 25% (P < 0.001). In CM patients maximal ROI production coincided with the nadir in PMN count. All patients dialysed with CM showed a clear increase in serum levels of Bb fragments, whereas PM-dialysed patients did not. In this respect, however, no clear time relationship was seen to the kinetics of ROI production, nor to the disappearance of neutrophils from the circulation. Evaluating a direct effect of the dialysis membranes on PMN demonstrated that incubation of neutrophils with hollow fibres of the CM but not of the PM in the absence of plasma induces significant ROI production by PMN. Our study thus indicates that ROI production by PMN during HD correlates to membrane biocompatibility. Furthermore, one might speculate that also independently from but perhaps in addition to complement activation, reactive oxygen products are critically involved in the generation of haemodialysis-associated neutrophil emigration.
Adult↗
The absence of 21-OH A and C4 B genes is a constant characteristic of the "Sardinian" HLA extended haplotype A30 Cw5 B18 BfF1 DR3 DRw52 DQw2.
The genomic DNA of 25 unrelated individuals with HLA haplotype A30 Cw5 B18 BfF1 DR3 D w52 DQw2 was digested with the restriction enzyme Taq I and hybridized with cDNA probes for C4 and 21-OH genes. Eighteen individuals and a non-Sardinian reference cell (DUCAF) were homozygous for the entire extended haplotype, six individuals were heterozygous for the HLA-A locus and homozygous for the rest of the same haplotype. All of the 18 homozygous individuals, four of the six heterozygous subjects and the DUCAF cell revealed the absence of two fragments at 3.2 and 2.4 kb corresponding to the 21-OH A gene, and the absence of fragments corresponding to the C4 B "long" or "short" gene. The contemporary absence of the 21-OH A and C4 B genes seems to be a constant characteristic of this extended haplotype in the Sardinian population and suggests that this and other extended haplotypes bearing C4 A or C4 B null alleles could be ancestral haplotypes which never duplicated at these loci.
Alleles↗
Anaphylactic reactions associated with anti-Chido Antibody following platelet transfusions.
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Anaphylaxis↗
An immunogenetic study of juvenile chronic arthritis.
Ninety-seven patients from Western Australia and Victoria suffering from juvenile chronic arthritis (JCA) for longer than 1 year were studied with particular reference to immunogenetic markers in the sub-groups of the disease. In the pauci-articular group, the antigens DR5, DR8 and BW35 were increased in frequency. The phenotypes within the sub-groups appeared distinctive despite the absence of any increase in the frequency of single antigens. Complement allotyping did not prove to be different from controls or within the sub-groups for JCA. This study supports the concept that patients with JCA have specific genetic characteristics and that sub-groups of the disease are genetically distinct.
Arthritis, Juvenile↗
Sclerosis multiplex in gypsies.
MS rarely occurs in gypsies in Hungary despite the high DR2 frequency. When it does occur, it has special features more resembling that of Asians than Central Europeans. In order to find correlation between the clinical observations and the immunogenetical data, the distribution of DQw1 subtypes was investigated by means of Eco RV - DQ beta RFLP in DR2 positive healthy gypsies and Hungarians, as well asin DR2-positive Hungarian and unselected gypsy MS patients. DQw6 correlated with MS susceptibility in Hungarians. This allotype was completely absent in healthy DR2-positive gypsies. DR2-positive gypsy MS patients, however, carried DQw6. No correlation of complement allotypes with the occurrence of MS was found in Hungarians, while a striking elevation of C4 Q0 occurred in gypsy MS patients compared with healthy individuals in the gypsy group. The absence of the DR2, DW2, DQw6 haplotype, and the frequency of C4A Q0 in healthy gypsies seems to be associated with the low MS prevalence, but genes outside this region might also influence the MS susceptibility.
Alleles↗
Heterogeneity of C4d and C3d and their complex formation with serum albumin.
High molecular weight (Mr around 175 KD) forms of C4d and C3d as well as free C4d and C3d (Mr about 40 KD) were demonstrable in normal human serum (NHS). Following in vitro C activation in NHS by delta IgG, the 40 KD C4d component increased markedly. By immunofixation it was shown that the high molecular forms of C4d and C3d reacted with biotinylated anti-human albumin IgG, whereas the 40 KD-free C4d and C3d fragments did not. Furthermore, the incorporation of anti-albumin IgG in the first dimensional gel in crossed immunoelectrophoresis caused retention of the 175 KD C4d component but not of free C4d. The 175 KD C4d had a distinctly higher electrophoretic migration velocity (post-albumin region) than the 40 KD C4d fragment. The C3d-, C4d-serum albumin complexes could not be dissociated by reducing agents (DTT, mercaptoethanol), a non-ionic detergent, or exposure to high and low ionic strength.
Complement Activation↗
Reading disability, attention-deficit hyperactivity disorder, and the immune system.
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Attention Deficit Disorder with Hyperactivity↗
Activation of the complement system in baboons challenged with live Escherichia coli: correlation with mortality and evidence for a biphasic activation pattern.
Activation of the complement system was studied in baboons that were challenged with live Escherichia coli. In the group challenged with a lethal dose (n = 4), the complement activation parameters C3b/c, C4b/c, and C5b-9 increased 13, 5, and 12 times the baseline value, respectively, during the first 6 h after the E. coli infusion, whereas in the group challenged with a sublethal dose (n = 10), they increased only moderately, by 2 to 3 times the baseline value. However, in this latter group, a more pronounced activation occurred at 24 h. Subsequent experiments showed that this second phase in complement activation started at 6 h after the challenge, at which time infused microorganisms had been cleared from the circulation. The simultaneous increase in C-reactive protein with this second phase suggested an endogenous activation mechanism involving this acute-phase protein. Levels of inactivated (modified) C1 inhibitor also increased in both groups, with peak levels of 2.5 times the baseline value at 24 h in the sublethal group and of 4 times at 6 h after the challenge in the lethal group. Thus, activation of complement in this animal model for sepsis occurs in a biphasic pattern, the initial phase mediated by the bacteria and the later phase mediated by an endogenous mechanism possibly involving C-reactive protein. The differences in complement activation between animals with lethal or sublethal sepsis support the hypothesis that complement activation contributes to the lethal complications of sepsis.
Animals↗
Correlation of the activation of the fourth component of complement (C4) with disease activity in systemic lupus erythematosus.
Levels of C4d, a fragment of C4 generated during activation of the classical complement pathway, were measured in the plasma of 48 patients with systemic lupus erythematosus, 11 with inactive (group 1), 23 with mildly active (group 2), 14 with moderately/severely active disease (group 3), and 30 healthy subjects. Levels of C3d, C4, and C3 were also measured and the C4d/C4 and C3d/C3 ratios calculated. C4d levels correlated with the degree of disease activity, being higher in group 3 than in group 2, in group 2 than in group 1, and in group 1 than in controls. C4d/C4 gave a similar result. Activation indices of the common complement pathway, C3d and C3d/C3, also correlated with disease activity, but in a non-linear relationship, failing to discriminate between patient groups. C4 and C3 showed no correlation with disease activity. These results indicate that indices of C4 activation, C4d and C4d/C4, provide a laboratory measure of disease activity in lupus patients, for whom an objective assessment of the severity of the disease is not readily available.
Adult↗
A long-term immunological study of childhood onset systemic lupus erythematosus.
Immunological dysregulation is an important cause of the development of systemic lupus erythematosus (SLE). Serological evaluation has been useful in the clinical management of patients and as a prognostic indicator. Sixteen patients who developed SLE as children were followed up for more than three years and immunological data collected. The results showed that (a) complement C3 concentration was lower in the active stage of SLE, especially during a major clinical exacerbation, but rarely preceded a major flare up. The concentration was often normal during the mildly to moderately active stage. In contrast, a low complement C4 concentration often preceded a major clinical exacerbation and could be of longer duration, sometimes persisting regardless of disease activity. (b) A T cell subset distribution study showed persistently low CD4 positive T cells in the peripheral blood of patients with SLE during the long term follow up, strongly suggesting that the intrinsic defect is mainly localised in T helper/inducer cells. These abnormal cellular defects did not tend to return to normal even in long term remission. (c) The persistently higher serum interleukin 2 and interleukin 2 receptor concentrations in SLE strongly suggested that the T cells were preactivated in vivo and that these phenomena might persist even in remission. (d) The best single parameter for predicting active SLE was anti-dsDNA. It was highly correlated with disease activity in most patients, and the asymptomatic increase of anti-dsDNA (greater than or equal to 60 U/ml, radioimmunoassay) was often followed by a major clinical exacerbation, especially in patients with a simultaneously low complement C4 concentration, suggesting that it might be an important warning sign of a major flare up. High dose steroids are indicated in this group of patients.
Adolescent↗
Association of Wegener's granulomatosis with HLA antigens and other genetic markers.
The frequencies of the HLA-A, B, C, DR, DQ antigens and of several other genetic markers in biopsy proved and well characterised patients with Wegener's granulomatosis were compared with control frequencies of the region. A highly significant increase in HLA-DR1 was found. The percentage combined frequency of DR1-DQw1 was significantly higher in patients than in the controls. Interestingly, association with the red cell enzyme GLOI and complement locus C4B was also seen. As both of these markers are either linked or within the major histocompatibility complex region (MHC) this is further evidence for the involvement of chromosome 6 in the pathogenesis of Wegener's granulomatosis. To understand the pathology of the disease fully molecular genetic studies of the MHC region are warranted.
Adult↗
Association of complement alleles C4AQ0 and C4B5 with rheumatoid arthritis in Koreans.
OBJECTIVE: To investigate the association of complement C4 allotypes with rheumatoid arthritis in Koreans. METHODS: 65 rheumatoid arthritis patients and 255 controls were typed for C4 allotypes and HLA-A, B, C, DR, and DQ antigens. RESULTS: The frequencies of C4AQ0 (32.3% v 14.9%, P < 0.005) and C4B5 (29.2% v 12.2%, P < 0.005) were significantly increased in rheumatoid arthritis patients compared with healthy control subjects. Among rheumatoid patients, the frequency of C4AQ0 was significantly increased in both the rheumatoid factor (RF) positive (27.3%) and the RF negative (66.7%) subgroups. The frequencies of C4B5 and HLA-DR4 were significantly increased only in RF positive subgroup. C4B5 was strongly associated with HLA-DR4, whereas C4AQ0 did not show association with DR4. CONCLUSIONS: In Koreans, C4AQ0 and C4B5 are associated with susceptibility to rheumatoid arthritis, as in the Japanese. C4B5 is strongly associated with HLA-DR4. C4AQ0 is considered to be a DR4 independent risk factor, and a disease susceptibility allele in linkage disequilibrium with C4AQ0 is suggested in Korean patients with rheumatoid arthritis.
Adult↗
Increased concentration of C4d complement protein in CSF in amyotrophic lateral sclerosis.
Plasma and CSF concentrations of C4d and the circulating immune complex to C1q were measured in 27 patients with amyotrophic lateral sclerosis (ALS) or cervical spondylosis. There was no significant difference among groups in plasma C4d or in plasma or CSF concentrations of the circulating immune complex to C1q. The ALS group, however, had a significantly higher CSF concentration of C4d than the group with cervical spondylosis, as well as a higher C4d index (CSF to plasma C4d ratio x serum to CSF albumin ratio). These results suggest that augmented complement activation in the CNS occurs in ALS. Increased CSF concentration of C4d or raised C4d index may serve as a basis for differentiating ALS from cervical spondylosis.
Adult↗
Complement alterations in the CSF of patients with amyotrophic lateral sclerosis.
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Amyotrophic Lateral Sclerosis↗
Differences in susceptibility to infection with Treponema pallidum (Nichols) between five strains of guinea pig.
Groups of 10 young male guinea pigs of inbred strains 2 and 13 and outbred strains Hartley A, Hartley B, and one deficient in the fourth component of complement (C4D) were infected intradermally with 80 X 10(6) Treponema pallidum (Nichols). The course of infection and production of antitreponemal antibody were examined. Strain C4D guinea pigs were the most susceptible to infection (100%); inbred strains 2 and 13 and outbred strain Hartley B showed 80-90% symptomatic infection; and the Hartley A strain was the least susceptible to infection (10%). Strain 13 animals responded with the highest antitreponemal antibody activity, and the Hartley A strain with the lowest. The results suggest that genetic factors or complement, or both, may influence the degree of susceptibility to infection with T pallidum in guinea pigs.
Animals↗
I (C3b/C4b inactivator) typing by agarose gel isoelectric focusing and immunoblotting technique.
Genetic polymorphism of I (C3b/C4b inactivator) was studied by the method of agarose gel isoelectric focusing followed by an immunoblotting technique. Serum or plasma samples were pretreated with neuraminidase. The method is rapid, and gives the simple and reliable patterns of I. The allele frequencies calculated from healthy Japanese individuals living in the western part of Japan were: IF* A = 0.126 and IF*B = 0.874.
Blood Proteins↗