Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Complement C1q”

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 1,765 records · Page 98Linked to original sources
PubMed1987

Fibroblast heterogeneity in scleroderma: Clq studies.

Fibroblast heterogeneity has been the basis of a pathogenetic theory of scleroderma in which one subpopulation of high collagen producing cells is expanded by selective growth. In studies by others using gingival cells, fibroblast membrane Clq receptor affinity correlates positively with collagen production. We have demonstrated distinctly higher amounts of Clq binding of fibroblasts from 2 patients with early scleroderma compared to late scleroderma and controls. These observations are consistent with the overgrowth of a normally occurring subpopulation of cells and provide support for clonal selection in the pathogenesis of scleroderma.

Adult↗
PubMed1987

Identification of the post-translational modifications of the core-specific lectin. The core-specific lectin contains hydroxyproline, hydroxylysine, and glucosylgalactosylhydroxylysine residues.

The core-specific lectin (CSL) synthesized and secreted by rat hepatocytes and the rat hepatoma H-4-II-E shows affinity for mannose and N-acetylglucosamine residues in the "core" region of asparagine-linked oligosaccharides. The CSL undergoes two stages of post-translational modification which result in an increase in its Mr from 24,000 to 26,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We have determined that the lectin undergoes hydroxylation of proline and lysine and that the hydroxylysine is glycosylated to form glucosylgalactosylhydroxylysine (GlcGalHyLys). CSL metabolically labeled with [3H]lysine and [3H]proline contains hydroxylated forms of proline and lysine. The mature form of the lectin can also be metabolically labeled with [3H]galactose. alpha,alpha'-Dipyridyl, an inhibitor of collagen prolyl and lysyl hydroxylases, prevents the metabolic incorporation of [3H]galactose and the post-translational increases in the Mr of the CSL, indicating that both events are dependent upon hydroxylation of proline and lysine. Virtually all of the hydroxylysine present in the CSL is recovered as glucosylgalactosylhydroxylysine after alkaline hydrolysis. The post-translational modifications of the CSL place it in a select family of secreted proteins which contain collagen-like sequences, including the pulmonary surfactant proteins, complement component C1q, and the 18 S asymmetric form of acetylcholinesterase.

2,2'-Dipyridyl↗
PubMed1985

The isotype and specificity of antiglobulins in BALB/c mice.

Antiglobulin activity was detected in the IgM class and the IgG1, IgG2a and IgG2b subclasses in normal and unstimulated BALB/c mice. There was an age related increase in their IgM antiglobulin, but this increase was not observed with IgG antiglobulin. Antiglobulin production could be induced by polyclonal activation of BALB/c mice with lipopolysaccharide, but this produces an increase in IgM antiglobulin only. IgM antiglobulin binding with mouse IgG1 and human IgG peaked on day 4 following lipopolysaccharide, whereas IgM antiglobulin binding with mouse IgG2a peaked around day 7. There was no IgM response with specificity for binding to mouse IgG2b. The level of IgG antiglobulin remained constant following polyclonal activation of BALB/c mice with lipopolysaccharide. Interestingly IgG antiglobulin binds preferentially with isologous IgG compared with heterologous IgG. Possible physiological roles have been discussed for the presence of these rheumatoid factors in normal mice.

Aging↗
PubMed1985

Enhancement of Clq binding activity by IgM rheumatoid factor.

Clq binding activity (ClqBA) averaged 18.1 +/- 14.5% (1 SD) in 28 rheumatoid arthritis (RA) sera (normal sera = 3.9 +/- 0.4%). Further analysis indicated that rheumatoid factor (RF) positive [RA (+)] sera averaged 30.4% ClqBA, significantly greater than the 3.9% ClqBA in RA RF negative [RA(-)] sera (p less than 0.01). In the RA(+) sera, RF titer correlated with ClqBA (r = +0.73). Addition of IgM RF to sera of normal, SLE, and RA(-) patients, as well as to aggregated IgG and reduced and alkylated aggregated IgG, resulted in significant increases in ClqBA, up to 14% in the latter group (p less than 0.01). Control IgM added to these same systems had no effect on ClqBA. IgM RF only slightly increased Clq binding of monomeric IgG.

Antigen-Antibody Complex↗
PubMed1985

Circulating immune complexes and rheumatoid arthritis.

Circulating immune complexes (CIC), as detected by the Clq binding assay (ClqBA) in sera from patients with rheumatoid arthritis (RA) were not demonstrable on analysis by ultracentrifugation on sucrose gradients. This discrepancy could be explained by the finding that polyethylene glycol 6000(PEG), used in the ClqBA to separate free radiolabelled Clq from complex bound Clq, increased the avidity of rheumatoid factor (RF), resulting in the formation of Clq binding RF IgM IgG complexes. Addition of purified RF IgM to normal human serum generated a positive ClqBA in a dose dependent way. The increased complex formation between RF IgM and IgG by PEG was also demonstrated in an enzyme linked immunoabsorbent assay and with sucrose gradients, where complexes became detectable when PEG was present. On the other hand RF IgM IgG Clq complexes obtained from the ClqBA dissociated upon removal of PEG. We conclude that high amounts of immune complexes, detected in RA sera by the ClqBA, are at least partly the result of in vitro complex formation between RF IgM and IgG. Therefore the results of this assay do not reflect the situation in the circulation in vivo.

Antigen-Antibody Complex↗
PubMed1986

The complete amino acid sequence of the A-chain of human plasma alpha 2HS-glycoprotein.

Normal human plasma alpha 2HS-glycoprotein has earlier been shown to be comprised of two polypeptide chains. Recently, the amino acid and carbohydrate sequences of the short chain were elucidated (Gejyo, F., Chang, J.-L., Bürgi, W., Schmid, K., Offner, G. D., Troxler, R.F., van Halbeck, H., Dorland, L., Gerwig, G. J., and Vliegenthart, J.F.G. (1983) J. Biol. Chem. 258, 4966-4971). In the present study, the amino acid sequence of the long chain of this protein, designated A-chain, was determined and found to consist of 282 amino acid residues. Twenty-four amino acid doublets were found; the most abundant of these are Pro-Pro and Ala-Ala which each occur five times. Of particular interest is the presence of three Gly-X-Pro and one Gly-Pro-X sequences that are characteristic of the repeating sequences of collagens. Chou-Fasman evaluation of the secondary structure suggested that the A-chain contains 29% alpha-helix, 24% beta-pleated sheet, and 26% reverse turns and, thus, approximately 80% of the polypeptide chain may display ordered structure. Four glycosylation sites were identified. The two N-glycosidic oligosaccharides were found in the center region (residues 138 and 158), whereas the two O-glycosidic heterosaccharides, both linked to threonine (residues 238 and 252), occur within the carboxyl-terminal region. The N-glycans are linked to Asn residues in beta-turns, while the O-glycans are located in short random segments. Comparison of the sequence of the amino- and carboxyl-terminal 30 residues with protein sequences in a data bank demonstrated that the A-chain is not significantly related to any known proteins. However, the proline-rich carboxyl-terminal region of the A-chain displays some sequence similarity to collagens and the collagen-like domains of complement subcomponent C1q.

Amino Acid Sequence↗
PubMed1982

Pharmacological modification of immunoregulatory T lymphocytes . II. Modulation of T lymphocyte cell surface characteristics.

Human peripheral blood lymphocytes were fractionated into non-T lymphocyte, T lymphocyte, theophylline resistant (TR) and theophylline sensitive (Ts) T lymphocyte subpopulations. The proportion of cells bearing surface membrane immunoglobulin (sIg), Clq, Ia antigen, beta 2 microglobulin and T lymphocyte specific antigens detected by monoclonal antibodies OKT3, OKT4, OKT5 and OKT8 was studied using immunofluorescent techniques. Incubation of T lymphocytes or TR lymphocytes with adenosine or impromidine, an H2 histamine agonist, under conditions previously shown to increase Fc gamma receptors and radioresistant suppressor cell activity, was found to increase the proportion of cells expressing readily detectable surface beta 2 microglobulin and the antigen detected by OKT8. Cells expressing OKT4 antigen declined and there was no change in OKT3, OKT5, Ia, Clq, sIg or Es receptor expression. These data indicate that the expression of T lymphocyte Fc gamma receptors, beta 2 microglobulin and the antigens detected by the monoclonal antibodies OKT4 and OKT8 are, at least in part, regulated by agents acting upon adenosine and H2 histamine receptors.

Adenosine↗
PubMed1984

The efficacy of plasma exchange in the removal of plasma components.

The efficacy of plasma exchange in the removal of immunoglobulins (IgG, IgM, IgA), complement components (C1q, C4, C3), alpha 1-antitrypsin, alpha 2-macroglobulin, and transferrin was studied by analysis of pre- and postexchange serum samples and the plasma removed both in a healthy volunteer and in five patients undergoing therapeutic plasma exchange. In the healthy volunteer, the measured reduction in serum concentration and the measured amount removed for each component was compared with values predicted by a physical model. For all components except IgM, the sum of the measured amount removed during the procedure and the calculated amount present in the circulation progressively exceeded the calculated intravascular amount present before plasma exchange. This was particularly the case for C4, C3, alpha 1-antitrypsin, and alpha 2-macroglobulin and may be explained by influx from the extra- to the intravascular compartment during the procedure. Influx also occurred in the patients. We conclude that, except for IgM, the actual amount of a component that has been removed should be assessed for proper evaluation of the efficacy of PE.

Blood Proteins↗
PubMed1984

[Lymphokine production in vitro by blood lymphocytes from patients with a defective or hyperactive immune system].

Blood lymphocytes from 8 patients with common variable immunodeficiency (CVID), 5 patients with signs of polyclonal activation of the immune system (1 SLE, 3 AILAP, 1 NHL) and 6 patients with various granulomatous diseases were examined for their capacity to produce lymphokines in vitro. Lymphocytes from 16 healthy individuals served as controls. To induce interleukin-2 (IL-2) and gamma-interferon (gamma-IFN) production lymphocytes were stimulated for 24 hrs with ConA or PHA or for 72 hrs with ConA + PMA + urea. alpha-IFN production was induced with Herpes simplex virus I (HSV) and the mycoplasma infected murine leukemia line L1210. Cell-free culture supernatants were harvested and IL-2 activity was determined by means of its growth promoting activity for a murine T-cell line (M-2). IFN activities were measured in a conventional virus plaque reduction assay. Besides lymphokine production the isolated cells were also examined for lymphocyte markers, mitogen responsiveness and NK activity. As compared to the control group, CVID lymphocytes exhibited a slightly enhanced IFN production and a moderately reduced IL-2 production. Three day preincubation in FCS containing medium enhanced the IL-2 production of control and patient lymphocytes. By contrast, preincubation of lymphocytes in medium supplemented with autologous serum no longer enhanced IL-2 production of CVID lymphocytes whereas it still did so for control lymphocytes. A striking finding was the impairment of IL-2 and IFN production in cultures of lymphocytes from patients with a polyclonally activated immune system. Notably lymphocytes from the three patients with angioimmunoblastic lymphadenopathy (AILAP) failed to produce significant amounts of lymphokines. Patients with granulomatous diseases (3 Morbus Behçet, 1 tuberculosis, 2 chronic granulomatous diseases) showed little alterations of their lymphokine production capacity. The results are compared with other lymphocyte parameters and are discussed in view of recent reports in the literature on lymphokine production in various diseases.

Adult↗
PubMedDate not supplied

Polymyalgia rheumatica and giant cell arteritis: circulating immune complexes.

Circulating immune complexes (CIC) were detected in a large population of patients with polymyalgia rheumatica (PMR) alone, PMR-giant cell arteritis (GCA), and GCA alone. CIC were found in the majority of patients studied. A direct correlation was observed between levels of CIC material and the erythrocyte sedimentation rate. The presence of immune complexes in the sera of patients with these disorders do not have diagnostic significance but may play an important role in their pathogenesis.

Aged↗
PubMed1982

Circulating immune complex levels in patients with gestational trophoblastic neoplasia.

The clinical course, human chorionic gonadotropin (HCG) levels, and serial circulating immune complex (CIC) levels in 21 patients with gestational trophoblastic neoplasia (GTN) were correlated for the evaluation of the relationship between CIC levels and trophoblastic tumor burden. CIC levels were normal in 18 of 21 patients at the time of presentation, and 2 of 3 patients who presented with elevated CIC levels had significant comorbid disease (toxemia and hepatitis). Nine patients were followed into gonadotropin remission, and all 9 developed an increase in CIC levels at the time of remission. It was concluded that CIC, at least as measured by two antigen-nonspecific techniques, is generally not elevated at initial presentation in the patient with GTN; this lack of an elevation is probably due to marked tumor antigen excess. Thus the in vivo importance of CIC as a "blocker" of host antitumor response at this stage is doubtful. After effective treatment as HCG levels return to normal, the demonstrated elevation in serial levels of CIC may reflect a return of adequate host immune response at a time of minimal tumor burden.

Adolescent↗
PubMed1983

Isolation of virus and antibody containing immune complexes from mink with Aleutian disease by affinity chromatography of equine complement clq.

Affinity chromatography on immobilized equine complement Clq was used for the isolation of complement-binding immune complexes in sera of mink infected with Aleutian disease virus. Immune complexes were isolated and quantitated from 4 of 5 infected mink, as early as 2 weeks after infection and before hypergammaglobulinemia had appeared. The quantity of immunoglobulin G in these immune complexes ranged from 180 to 370 micrograms/ml serum. There were no Clq-binding immune complexes found in mink which were negative for Aleutian disease antibody. Using 125I-labeled BSA-anti-BSA complexes, we demonstrated that the affinity columns bound selectively immune complexes which had formed in antibody excess, whereas immune complexes in antigen excess were not bound. By neutralization of sensitized virus with anti-mink IgG serum, non Clq-binding immune complexes were also detected, which indicates that circulating immune complexes in persistently infected mink are heterogeneous as far as their reactivity with equine Clq is concerned.

Aleutian Mink Disease↗