Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Complement C2”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources
PubMed1976

Synthesis of the second component of complement by long-term primary cultures of human monocytes.

A method has been developed for preparation of confluent monolayers of human monocytes from small volumes of blood and for maintenance of these pure monocyte cultures for up to 16 wk in vitro. These cells phagocytosed 5.7 mum diameter latex beads, rosetted with erythrocytes coated with IgG or with C3, killed Listeria monocytogenes, and synthesized both lysozyme and the second component of complement. Lysozyme was secreted at a rate of approximately 50,000 mol/min per cell for at least 12 wk in cultures. The maximal rate of C2 synthesis and secretion was considerably less; i.e., approximately 30 mol/min per cell between the 2nd and 12th wk in culture. Monocytes produced little C2 during the first 6 days in culture after which a marked increase in the rate of C2 production was noted. This increase was coincident with morphologic evidence of monocyte maturation.

Bacteriolysis↗
PubMed1976

The serine protease nature of the C3 and C5 convertases of the classical and alternative complement pathways.

Activated Factor B, incorporated into the cobra venom factor (CVF)-dependent C3/C5 convertase, was inactivated by diisopropylfluorophosphate (DFP). Inactivation was time- and dose-dependent and was enhanced by the presence of substrate. Treatment of the zymogen of Factor B with DFP effected significant inactivation. Incorporation of [3H]diisopropylphosphate into the zymogen and into the activated form of Factor B was demonstrated after [3H]DFP treatment and subsequent electrophoresis of the proteins on polyacrylamide gels containing sodium dodecyl sulfate. Inactivation of activated C2 incorporated into the classical C5 convertase was observed on DFP treatment of the enzyme. DFP also reduced the activity of the C2 zymogen. The description of their serine proteinase nature further emphasizes the close structural and functional relationship of C2 and Factor B.

Complement C2↗
PubMed1980

Analysis of the anticomplementary activity in sera of three African patients with parasitic and bacteriological infections.

The sera of three different patients from Togo, Africa were investigated with respect to their complement profile. The three patients were suffering from parasitic (Onchocerca volvulus) and bacteriological (Treponema pertenue) diseases. The total hemolytic activity (50% hemolytic complement) was markedly depressed. The analysis of the individual complement components revealed the the titers of C1, C2, C3, and C4 were lowered up to 90%, indicating an activation of the classical pathway of complement. Addition of the patients' sera to normal human serum induced a temperature-dependent consumption of C4 and C2, whereas C3 was not affected. This activity in the patients' sera eluted from a Sephadex-G-200 column with the 19 S peak and could be identified as the activated form of the first component of the complement system. The reason for the presence of activated C1, C1 in the patients' sera resides in the absence of functionally active C1 inactivator.

Adult↗
PubMed1978

[Treatment of hereditary angioneurotic edema with androgens].

Hereditary angioedema (HANE) is a rare, life-threatening disease due to the deficiency of C1 inhibitor (C1 Inh). Androgen therapy has been recently shown to be effective for prophylaxis of Hane attacks. Since life-long androgen therapy may be hazardous, this study was designed to define the minimal doses required for effectiveness. Ten patients from six different families were treated during cumulative 73 months by danazol and/for methandrostenolone. One tablet/day of either drug was the minimal requirement to prevent any attack in all patients. When 3 tablets/day were given, complement abnormalities were simultaneously rapidly reversed. When 1 tablet/day was given the biological effect was barely detectable, except for C2. Serum C2 levels may, therefore, represent the best criteria of androgen therapy effectiveness. Thus, an excellent clinical result can be obtained with much lower doses of androgens than previously stated. This result seemed important with respect to the serious dose-dependent risk of androgens.

Adult↗
PubMed1976

Evidence that C1s participates in the alternative complement pathway.

Purified C1s, subcomponent of C1, induced electrophoretic conversion of factor B and consumption of hemolytic C3 and C5 in sera genetically deficient in C2 or C4. Blocking of the hemolytic activity of C1s in C2-deficient serum by F(ab')2 anti-C1s resulted in inhibition of the alternative pathway, as indicated by the failure of zymosan or cobra venom factor to induce comsumption of C3 and C6. Zymosan also failed to activate the alternative pathway when C1s was absorbed from C1r-deficient serum using a solid immunoabsorbent. These data, showing that C1s participates in the alternative pathway under certain experimental conditions, suggest the interesing possibility that C1s is important in the activation sequence of both the classical and the alternative pathway more generally.

Animals↗
PubMed1982

Hemolytic efficiency of cell-bound IgM: evidence that IgM-C1 complexes activate C4 molecules not hemolytic with homologous C2--C9.

The hemolytic efficiency of rabbit-anti-Forssman IgM antibody depends on the source of complement components. With whole guinea pig complement as few as one in 10 IgM molecules was hemolytic; it was found that with purified guinea pig C1, C4, and C2 components and with rat late-acting components, all IgM molecules were hemolytic. Evidence indicates that the block occurred as a result of generating at least two different cell-bound C4 molecules, one of which was not competent with homologous late-acting components.

Animals↗
PubMed1978

Lymphokine and synthesis of complement by guinea pig spleen cells.

Lymphokine preparations have been obtained from normal guinea pig spleen cells stimulated in vitro by optimal doses of insoluble Concanavalin A. The biological activity of these preparations was estimated by Macrophage Inhibition Tests performed with peritoneal cells from identical guinea pigs. Addition of these preparations to culture of normal adherent guinea pig spleen cells, gives rise to a dose related inhibition of the normal synthesis of C2, the second component of the complement system, by these latter cells. This inhibition of synthesis, appears to be due to a functional effect of lymphokine on C2-producing cells and not to a cytotoxic effect. Preliminary results indicate that the same lymphokine preparations can have a stimulatory rather than an inhibitory effect on synthesis of haemolytic C1 by the same cells.

Animals↗
PubMed1983

Extended MHC haplotypes in 21-hydroxylase-deficiency congenital adrenal hyperplasia: shared genotypes in unrelated patients.

HLA, complement, and glyoxalase I alleles were studied in 29 families in which at least one member has classical 21-hydroxylase-deficiency congenital adrenal hyperplasia. A rare complement allele, C4B*31, was found in over 20% of the haplotypes defined in these families and was always part of the complement haplotype BF*F, C2*C, C4A*Q0, C4B*31 (abbreviated FCO,31). The haplotype containing this rare set of complement alleles always carried the rare HLA allele, HLA-Bw47, usually carried HLA-A3, and almost always had the alleles HLA-Cw6, HLA-DR7, and the glyoxalase I (GLO) allele GLO1. Thus over 20% of the haplotypes in the population studied contained all or almost all of the rare extended haplotype HLA-(A3), Bw47, Cw6,DR7, FCO,31, GLO 1. 3 other haplotypes were each found twice in unrelated patients concordant for their disease phenotype and ethnic background. Extended MHC haplotypes may be markers for different genetic mutations causing 21-hydroxylase deficiency.

Adrenal Hyperplasia, Congenital↗
PubMed1977

Production of the second component of complement by human monocytes: stimulation by antigen-activated lymphocytes or lymphokines.

Human peripheral blood mononuclear cells cultured in the presence of antigen produced hemolytically active second complement component earlier and in larger amounts than did control cultures of the same cells without antigen. The increased amount of C2 in culture supernates came primarily from the adherent cell population and was due to increased synthesis as demonstrated by inhibition with 10(-4) M cycloheximide. Purified adherent monocytes produced more C2 when exposed to lymphokine-rich supernates from antigen-stimulated lymphocytes than when exposed to control supernates from unstimulated lymphocyte cultures. The increased synthesis of C2, which appeared to be mediated by a lymphokine, was partially inhibited specifically by 0.025 M alpha-L(-) fucose, a sugar which has previously been shown in inhibit the response of macrophages to migration inhibitory factor.

Antigens↗
PubMed1980

Effect of histamine on monocyte complement production. II. Modulation of protein secretion, degradation and synthesis.

Using immunofluorescence and pulse-label studies with 3H-labelled amino acids, histamine was shown to inhibit the secretion of newly synthesized C2, C4, C3, factor B and beta 1H globulin by monocytes in culture. The findings suggested that protein synthesis was decreased, and that the degradation of newly synthesized intracellular protein was increased in histamine-treated monocytes. The observations that all monocytes in cultures containing histamine stained for C2, C4, and C3, factor B and beta 1H, when secretion was impaired, shows that all monocytes synthesize these proteins. These results demonstrate a negative feedback loop on C3 and C5 cleavage. The anaphylotoxins, C3a and C5a, formed as a result of C3 and C5 cleavage, release histamine from mast cells and basophils. Histamine, by inhibiting the production of C4, C2, and C3 and factor B by mononuclear phagocytes, inhibits further C3 and C5 cleavage by restricting the formation of C42, C423b and C3bBbP.

Amino Acids↗
PubMed1990

C2 reference typing report.

Thirty samples contributed by seven laboratories to the VIth Complement Genetics Workshop were analyzed by isoelectric focusing and immunoblotting with a specific antihuman C2 antibody for the study of the polymorphism of native, activated and desialated C2. This study allowed to compare almost all the C2 variants so far described and also several 'new variants'. According to our results, the C2 system consists of nine structural variants at the protein level which include the common C2 C, the less common C2 B (in Caucasoids), four rare acidic and three rare basic variants. The polymorphic site for the basic variants is carried by the C2a fragment. Typing of desialated C2 is necessary to identify rare acidic or basic variants, especially the C2 BH and C2 BJ variants which seem difficult to be recognized in the native protein.

Antibodies↗
PubMed1978

Functional and biochemical properties of the early classical complement system of mice.

Mouse serum and EDTA plasma were subjected to low ionicity precipitation, gel filtration, and ion exchange chromatography in an attempt to purify C1, C4, and C2 to functional and chemical homogeneity. In marked contrast to human and guinea pig components, those of the mouse could not be separated by these techniques. Except for partial separation of C1 from C4 and C2 on DE-52 cellulose columuns with EDTA in the eluting buffers, there was no separation of those three components on ion exchange chromatographic columns. Sephadex G-200 gel filtration columns, or with precipitation of euglobulins from serum or plasma. Generation of EAC142 by incubation of EA in whole serum followed first order kinetics when mouse serum was used and second (or greater) order kinetics when human or guinea pig sera were used. Generation of EAC142 by incubation of EA in whole mouse serum followed by incubation in EDTA containing buffers resulted in rapid loss of all three activities from the cell. These experiments indicated that there were significant differences between the early classical C system of mice and those of human and guinea pig. In addition, they indicated that under a variety of in vitro conditions, murine C1, C4, and C2 behaved biochemically and functionally as a unit. The reasons for the major differences in behavior of the murine C components with not become clear until methods to stabilize their function are found so that they can survive multiple purification steps.

Animals↗
PubMed1977

Serum immune complexes in membranoproliferative and other glomerulonephritides.

Immune complexes were detected in the serum of patients with membranoproliferative glomerulonephritis (MPGN) Types I and II, systemic lupus erythematosus (SLE), and acute poststreptococcal glomerulonephritis (AGN) by sucrose gradient ultracentrifugation and by measurement of Clq binding activity (Clq-BA). Clq-BA was more sensitive in detecting complexes than was gradient ultracentrifugation. By gradient ultracentrifugation, the sedimentation velocities of the complexes in the three diseases were similar, ranging from 13S to 19S. This range corresponds to that observed by others in experimental chronic serum sickness nephritis. The complexes isolated by gradient ultracentrifugation always contained C3, usually IgG and C4, and in some patients with SLE and AGN, IgM. In MPGN, IgM and IgA could be present in glomerular deposits when not present in circulating complexes. In this disease also, serum complement levels were poor predictors of the presence of complexes. With increased Clq-BA, the levels of Clq, C4, and C2 could be normal or reduced and there was no correlation with C3 levels. With few exceptions, the clinical status of the patients with MPGN correlated well with Clq-BA.

Acute Disease↗
PubMed1982

[Hereditary complement deficiencies].

Complement deficiencies of all nine C-components have been observed. Hereditary defects of early components of the classical pathway - C1, C4, C2 - are often associated with diseases of the immuncomplex-type especially with systemic lupus erythematosus, dermatomysitis, vasculitis and nephritis. Deficiencies of C3 and C3b inactivator are linked to severe and recurrent bacterial infections. Patients with hereditary defects of the so-called late components, C5-C9, show increased susceptibility to recurrent disseminated infections by neisseria gonorrhoeae and meningitidis. The most frequent of the defects of the complement system is the hereditary deficiency of C1-inactivator which is associated with hereditary angioneurotic edema. In this paper the C-defects and their genetics are described and possible pathomechanisms are discussed.

Complement Activating Enzymes↗
PubMed1980

Biosynthesis of the complement components and the regulatory proteins of the alternative complement pathway by human peripheral blood monocytes.

Short-term cultures of human peripheral blood monocytes were shown to synthesize the alternative pathway complement components C3, factors B (B) and D (D), and properdin, the regulatory proteins C3b inactivator (C3bINA) and beta 1H, in addition to C2, C4, and C5. B, D, properdin, C3bINA, and C2 were detected by functional assays, whereas beta 1H, C4, C3, and C5 could only be detected using immunochemical procedures. Immunoperoxidase localization studies showed that all the cells in each culture contained each component, so it is possible that all monocytes synthesize each component. It is concluded that cells of the monocyte-macrophage series form a mobile source of complement components and regulatory proteins which can be concentrated at sites of inflammation.

Cells, Cultured↗
PubMed1985

Purification and characterization of the C3 convertase of the classical pathway of human complement system by size exclusion high-performance liquid chromatography.

The C3 convertase of the classical pathway of the complement system is a liable complex, C4b,2a, and is activated by limited proteolysis of two components, C4 and C2, by C1s. By utilizing iodine-treated C2 and size exclusion high-performance liquid chromatography (HPLC), we have succeeded in isolating for the first time the classical pathway C3 convertase. Size exclusion HPLC demonstrated that the apparent molecular mass of the C3 convertase was 280K daltons. The C3 convertase decay-dissociates spontaneously into C4b and C2a. The decay-dissociation is a temperature-dependent reaction and the half-lives of the C3 convertase at 24, 30, and 37 degrees C were estimated to be 400, 180, and 60 min, respectively. The decay-dissociation was also dependent on pH and was accelerated by increasing pH. In addition, the decay-dissociation of the C3 convertase was accelerated by C2b. This result suggests that C2b acts as a feedback inhibitor on the activation of the classical pathway of complement system.

Chemical Phenomena↗