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Results for “Complement System Proteins”

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PubMed1977

Hydroxyproline fractions in serum and urine of rats during wound healing.

Total hydroxyproline in urine and free hydroxyproline, free and peptide hydroxyproline and protein bound hydroxyproline in serum are measured during wound healing in rats. The free and free+peptide fractions vary in concert with each other and with urine hydroxyproline. Protein bound hydroxyproline fractions take a very different course and behave as an acute phase reactant. The results suggest that protein bound hydroxyproline does not mirror collagen turnover but may be more relevant to C1q or complement metabolism.

Animals↗
PubMed1987

Carbohydrate interference of complement-dependent cell lysis.

The antibody-mediated cytotoxicity of three autoreactive sera, an allogeneic hyperimmune serum and a xenogeneic hyperimmune serum was abrogated by the presence of either glucosamine, galactosamine, lactulose or lactose. This inhibition could be overcome in a dose-dependent fashion by increasing the amount of complement in the cytotoxicity assay, but not by increasing the amount of antibody. Furthermore, the inhibition was specific for these sugars in that isomers and N-acetylated derivatives were not inhibitory. The results suggest that these sugars directly blocked events of the complement cascade.

Animals↗
PubMed1989

Iron-binding proteins and free iron in synovial fluids of rheumatoid arthritis patients.

Iron-binding proteins (lactoferrin, transferrin and ferritin) and free iron were measured in synovial fluid (SF) from 30 patients with rheumatoid arthritis (RA) and 20 osteoarthritis (OA) patients. The iron-binding proteins except transferrin were significantly increased in RA SF as compared with OA SF. Similarly, free iron was also significantly higher in RA SF than in OA SF, whereas the ferritin saturation index, transferrin saturation index and bound iron were more significantly decreased in RA SF than in OA SF. These results suggest that RA SF contains sufficient micromolar amounts of free iron to allow hydroxyl radical formation. Also the capacity of iron-binding proteins to bind free iron is inadequate in the presence of a large amount of iron-binding proteins which are present in RA SF.

Antigen-Antibody Complex↗
PubMed1996

Relationship between anticomplement in seminal plasma and complement in follicular fluid associated with outcome in an in vitro fertilization program.

PURPOSE: The study was conducted to evaluate levels of anticomplement in seminal plasma and levels of complement in follicular fluid, in correlation with fertilization and pregnancy rate after in vitro fertilization and intracytoplasmic sperm injection programs. MATERIALS AND METHODS: Anticomplement levels were determined in 70 couples undergoing in vitro fertilization therapy. In 15 of these couples, complement levels were measured. Anticomplement and complement levels were also determined in an additional 21 couples (apart from the 70 couples) undergoing intracytoplasmic sperm injection treatment. RESULTS: A correlation was found between fertilization rate and anticomplement levels in the seminal plasma (r = 0.4, P < 0.01) after standard in vitro fertilization. No correlation was found in the intracytoplasmic sperm injection group, or observed between complement levels and any parameter examined in both groups. Pregnancy occurred only in those couples with an anticomplement:complement ratio below 0.49. CONCLUSIONS: Determination of anticomplement and complement levels may contribute to the assessment of a successful outcome of in vitro fertilization/intracytoplasmic sperm injection.

Complement Inactivator Proteins↗
PubMed1999

Complement-mediated lysis of cultured osteosarcoma cell lines using chimeric mouse/human TP-1 IgG1 and IgG3 antibodies.

Osteosarcoma is the commonest malignant tumour of the bones. The presence of micrometastases at the time of primary diagnosis is associated with poor prognosis. Despite developments in surgery and aggressive chemotherapy, about 50% of the patients still succumb to the disease. Thus, there is a need to develop alternative treatment modalities. One such strategy is to use antibodies with improved effector functions. The two monoclonal antibodies, TP-1 and TP-3, recognize a tumour-associated antigen on human osteosarcoma cells. In the present study, we describe the cloning of the TP-1 variable genes, and the production of complete chimeric mouse/human monoclonal antibodies. Constructs containing the constant genes from human IgG1, IgG3 or a mutant IgG3 with a shortened hinge region, called m15, were expressed in the mouse myeloma cell line, NS0. The m15 mutant has been shown to be very potent in triggering complement-mediated lysis. Our goal was to investigate whether this mutant could overcome the complement protection on human osteosarcoma cells, which is generally present on all human cells. We found that the target cells expressed several membrane-bound complement inhibitors, and that masking of these inhibitors rendered the cells sensitive to lysis. The m15 mutant exhibited greater lytic activity than both IgG3 and IgG1, although it could not cause extensive killing of the target cells alone.

Animals↗
PubMed2005

Complement C2 receptor inhibitor trispanning: from man to schistosome.

Horizontal gene transfer (HGT), in relation to genetic transfer between hosts and parasites, is a little described mechanism. Since the complement inhibitor CRIT was first discovered in the human Schistosoma parasite (the causative agent of Bilharzia) and in Trypanosoma cruzi (a parasite causing Chagas' disease), it has been found to be distributed amongst various species, ranging from the early teleost cod to rats and humans. In terms of evolutionary distance, as measured in a phylogenetic analysis of these CRIT genes at nucleotide level, the parasitic species are as removed from their human host as is the rat sequence, suggesting HGT. The hypotheses that CRIT in humans and schistosomes is orthologous and that the presence of CRIT in schistosomes occurs as a result of host-to-parasite HGT are presented in the light of empirical data and the growing body of data on mobile genetic elements in human and schistosome genomes. In summary, these data indicate phylogenetic proximity between Schistosoma and human CRIT, identity of function, high nucleotide/amino acid identity and secondary protein structure, as well as identical genomic organization.

Amino Acid Sequence↗
PubMed2003

Effect of myasthenic immunoglobulin G on motor end-plate morphology.

This study was undertaken to clarify the role of complement in acetylcholine receptor loss and degeneration of the postsynaptic membrane in myasthenia gravis (MG). We examined the end-plate morphology in rats with passively transferred immunoglobulin G (IgG) from myasthenic patients and the effect of complement by treatment of the rats with cobra venom factor. We injected peroxidase-labeled alpha-BuTx (P-BuTx) into the extensor digitorum longus (EDL) muscle to label the motor end-plates. Three hours later, 100 mg of IgG from MG patients or healthy controls was injected into the tail vein. The EDL was removed 48 hours after the injection of IgG. The presence of macrophages and degeneration of the postsynaptic membrane were seen in 4 of 6 IgG samples from MG patients and a decrease in AChRs in the other 2 samples. These changes were reversed completely by treatment with cobra venom factor in all but one case in which the end-plates were severely degenerated. Injection of MG IgG only never induced end-plate morphology changes. The results suggest that complement has a critical role in degeneration of the postsynaptic membrane and AChR loss at the motor end-plates in the passively transferred model and probably in human MG.

Adolescent↗
PubMed2006

Streptococcus agalactiae CAMP factor/protein B does not bind to human IgG.

CAMP factor is an extracellular cytolytic protein produced by Streptococcus agalactiae. CAMP factor has been reported to bind the Fc fragments of immunoglobulin G (IgG) and has therefore also been called protein B, in analogy to protein A of Staphylococcus aureus. We attempted to characterize the interaction of protein B with IgG in more detail. In contrast to protein A, CAMP factor does not inhibit the activation of complement by hemolysin antibodies bound to sheep red cell surfaces. IgG also failed to inhibit the co-hemolytic activity of CAMP factor, which is in disagreement with previous findings. After co-incubation, CAMP factor and IgG were cleanly separated by gel filtration, indicating that no binding had occurred.

Bacterial Proteins↗
PubMed2001

Ultrastructural damage of Trypanosoma cruzi epimastigotes exposed to decomplemented immune sera.

The susceptibility of Trypanosoma cruzi epimastigotes to lysis by normal or immune sera in a complement-dependent reaction has been reported, but the effects induced directly by immune serum depleted of complement remain unstudied. The aim of this work was to study the ultrastructural alterations induced in T. cruzi epimastigotes by immune mouse or rabbit sera with or without complement. A local isolate of T. cruzi (Queretaro) was used in all experiments. Immune sera were raised in both mouse and rabbit by immunization with T. cruzi epimastigote antigens. Light microscopy showed intense agglutination of epimastigotes when incubated with decomplemented mouse or rabbit immune sera. A distinctive ultrastructural feature of this agglutination pattern was the fusion of plasma membranes and a pattern of intercrossing between subpellicular microtubules. Agglutination was associated with fragmentation of nuclear membranes and swelling of cytoplasm, Golgi cisternae, endoplasmic reticulum, mitochondria and kinetoplast membranes. Agglutinated parasites also incorporated trypan blue stain. Results of [3H]-thymidine incorporation confirmed that epimastigotes exposed to specific antibodies in the absence of complement were incapable of proliferating. Ultrastructural changes observed in epimastigote micrographs incubated with decomplemented immune mouse sera were statistically significant (P<0.001) when compared with results obtained from images after incubation with decomplemented normal mouse sera.

Animals↗