1
|
Guo WX, Ghebrehiwet B, Weksler B, Schweitzer K, Peerschke EI. Up-regulation of endothelial cell binding proteins/receptors for complement component C1q by inflammatory cytokines. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1999; 133:541-50. [PMID: 10360628 DOI: 10.1016/s0022-2143(99)90183-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Endothelial cells express a variety of receptor systems involved in humoral defense, including receptors for the collagen-like and globular domains of the complement component C1q, designated cC1qR and gC1qR, respectively. In the present study a microvascular endothelial cell line was used to test the hypothesis that expression of these C1q-binding proteins may be affected by vascular inflammatory reactions. The results demonstrate that the expression of both cC1qR and gC1qR by bone marrow vascular endothelial cells is up-regulated by inflammatory mediators, interferon-gamma, tumor necrosis factor-alpha, and lipopolysaccharide (Escherichia coli, 055:B5) in a dose- and time-dependent manner, as detected by enzyme-linked immunosorbent assay. cC1qR and gC1qR expression increased significantly (P < .05) within 4 to 7 hours and doubled after 22 hours of stimulation. 3H-thymidine incorporation studies and direct cell counts confirmed that increased C1qR expression was not due to increased cell proliferation. Northern blot analysis revealed that the up-regulation of cC1qR and gC1qR protein expression was preceded by increases in corresponding mRNA levels, suggesting increased gene transcription. Indeed C1qR mRNA up-regulation was prevented by actinomycin D, and C1qR protein synthesis was inhibited by cycloheximide. Bone marrow vascular endothelial cell exposure to C1q, however, did not alter cC1qR or gC1qR expression, but up-regulation of the leukocyte adhesion molecule ICAM-1 was noted in the presence of aggregated C1q. The up-regulation of C1qR by inflammatory mediators and the ability of C1q itself to increase ICAM-1 expression suggest a potential role for these binding sites in vascular inflammation and immune injury.
Collapse
Affiliation(s)
- W X Guo
- Department of Pathology, and Medicine, The Joan and Sanford I. Weill College of Medicine of Cornell University, New York, New York, USA
| | | | | | | | | |
Collapse
|
2
|
Nepomuceno RR, Tenner AJ. C1qRP, the C1q Receptor That Enhances Phagocytosis, Is Detected Specifically in Human Cells of Myeloid Lineage, Endothelial Cells, and Platelets. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.4.1929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
The complement component C1q can interact with a variety of different cells, resulting in multiple functional consequences depending on the cell type. mAbs R3 and R139, which recognize a 126,000 Mr (reduced) cell surface protein, are able to abrogate the C1q-mediated enhancement of monocyte phagocytosis. The cDNA encoding this C1q receptor that modulates phagocytosis, C1qRP, has recently been cloned. Using a DNA probe based on the coding region of the receptor, Northern blot and RT-PCR analysis of RNA isolated from different cell types showed C1qRP expression in cells of myeloid origin and in endothelial cells, but not in cells of lymphoid origin nor in the HeLa epithelial-like cell line or iliac artery smooth muscle cells. FACS analysis of cell surface expression of C1qRP, as detected by mAb R139 and R3, corresponded in all cases to the mRNA levels detected. Using the anti-C1qRP mAb, the 126,000 Mr receptor was also detected in lysates of human platelets. Interestingly, C1qRP is not expressed by the promyelocytic leukemia cell line HL-60, and differentiation of these cells with various chemical compounds did not induce C1qRP expression. It has been reported that C1q can induce specific receptor-mediated responses in fibroblasts. However, RNA and cell surface expression analysis for C1qRP indicate that this particular C1q receptor is not expressed by either human gingival or human skin fibroblasts. These data demonstrate selective expression of C1qRP in specific cell types and support the hypothesis that there is more than one C1q receptor mediating the diverse responses triggered by C1q.
Collapse
Affiliation(s)
- Ronald R. Nepomuceno
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697
| | - Andrea J. Tenner
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697
| |
Collapse
|
3
|
Barron LG, Meyer KB, Szoka FC. Effects of complement depletion on the pharmacokinetics and gene delivery mediated by cationic lipid-DNA complexes. Hum Gene Ther 1998; 9:315-23. [PMID: 9508049 DOI: 10.1089/hum.1998.9.3-315] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We show that lipoplexes activate complement in human serum in vitro and deplete complement when administered intravenously (i.v.) to mice. This raised the possibility that complement proteins might alter gene expression mediated by lipoplex in animals. To investigate this phenomenon, complement levels were depleted to less than 5% in ICR mice by intraperitoneal (i.p.) injection of cobra venom factor and anti-C3 antibodies. The pharmacokinetics and distribution of radio labeled DOTAP-cholesterol (1.0:0.9 molar ratio)-DNA (5:1 positive charge ratio) complexes containing 131I-labeled p-hydroxybenzamidine phosphatidylethanolamine and 125I-labeled DNA were measured in mice after i.v. administration. Greater than 75% of the injected lipoplex appeared in the lungs 5 min following injection. The lipid and DNA were eliminated from the lungs at a constant ratio. Distribution in various organs was not affected by complement depletion. Expression of luciferase was highest in the lungs and showed a dose-dependent increase as the amount of DNA injected increased from 3 to 60 microg. Reporter gene expression was not affected by complement depletion. In addition, complement depletion had no effect on either the distribution or gene expression in the heart, spleen, or liver. We conclude that cationic lipid-DNA complexes interact with serum complement proteins upon i.v. injection in mice, but this interaction does not influence the lipofection efficiency or systemic distribution of the lipoplex.
Collapse
Affiliation(s)
- L G Barron
- Department of Biopharmaceutical Sciences, School of Pharmacy, University of California, San Francisco 94143-0446, USA
| | | | | |
Collapse
|
4
|
Klickstein LB, Barbashov SF, Liu T, Jack RM, Nicholson-Weller A. Complement receptor type 1 (CR1, CD35) is a receptor for C1q. Immunity 1997; 7:345-55. [PMID: 9324355 DOI: 10.1016/s1074-7613(00)80356-8] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Molecular definition of the cellular receptor for the collagen domain of C1q has been elusive. We now report that C1q binds specifically to human CR1 (CD35), the leukocyte C3b/C4b receptor, and the receptor on erythrocytes for opsonized immune complexes. Biotinylated or radioiodinated C1q (*C1q) bound specifically to transfected K562 cells expressing cell surface CR1 and to immobilized recombinant soluble CR1 (rsCR1). *C1q binding to rsCR1 was completely inhibited by unlabeled C1q and the collagen domain of C1q and was partially inhibited by C3b dimers. Kinetic analysis in physiologic saline of the interaction of unlabeled C1q with immobilized rsCR1 using surface plasmon resonance yielded an apparent equilibrium dissociation constant (K[eq2]) of 3.9 nM. Thus, CR1 is a cellular C1q receptor that recognizes all three complement opsonins, namely, C1q, C3b, and C4b.
Collapse
Affiliation(s)
- L B Klickstein
- Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | | | | | |
Collapse
|
5
|
Gorgani NN, Parish CR, Easterbrook Smith SB, Altin JG. Histidine-rich glycoprotein binds to human IgG and C1q and inhibits the formation of insoluble immune complexes. Biochemistry 1997; 36:6653-62. [PMID: 9184145 DOI: 10.1021/bi962573n] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Purification of the complement component C1q from human serum using an established method resulted in the copurification of two 30 kDa proteins with an N-terminal sequence identical to human histidine-rich glycoprotein (HRG). Therefore, to explore the possibility that HRG can interact with C1q, we examined the ability of 81 kDa (native) and the 30 kDa proteins (presumably proteolytic N-terminal fragments of HRG) to bind to C1q, using both ELISA and optical biosensor techniques. Both forms of HRG were found to bind to the human complement component C1q and also to purified human and rabbit IgG by ELISA. Kinetic analyses of the HRG-C1q and HRG-IgG interactions using the IAsys biosensor indicate two distinct binding sites with affinities Kd1 0.78 x 10(-8) M and Kd2 3.73 x 10(-8) M for C1q, and one binding site with affinity Kd 8.5 x 10(-8) M for IgG. Moreover, the fact that both native and 30 kDa HRG bind to C1q and to IgG suggests that the IgG and C1q binding regions on HRG are located in the 30 kDa N-terminal region of the HRG molecule. The Fab region of IgG is likely to be involved in the HRG-IgG interaction since HRG also bound to F(ab')2 fragments with an affinity similar to that seen with the complete IgG molecule. Interestingly, the binding between HRG and IgG was significantly potentiated (Kd reduced from 85.0 to 18.9 nM) by the presence of physiological concentrations of Zn2+ (20 microM). Conversely, the presence of Zn2+ weakened the binding of HRG to C1q (Kd increased from 7.80 to 29.3 nM). Modulation of these interactions by other divalent metal cations was less effective with relative potencies being Zn2+ > Ni2+ > Cu2+. An examination of the effect of native and 30 kDa HRG on the formation of insoluble immune complexes (IIC) between ovalbumin and polyclonal rabbit anti-ovalbumin IgG revealed that physiological concentrations of HRG can markedly inhibit IIC formation in vitro. The results show that human HRG binds to C1q and to IgG in a Zn2+-modulated fashion, and that HRG can regulate the formation of IIC in vitro, thus indicating a new functional role for HRG in vivo.
Collapse
Affiliation(s)
- N N Gorgani
- Division of Immunology and Cell Biology, The John Curtin School of Medical Research, Australian National University, Canberra, ACT
| | | | | | | |
Collapse
|
6
|
Marsh HC, Ryan US. Therapeutic Effect of Soluble Complement Receptor Type 1 in Xenotransplantation. Xenotransplantation 1997. [DOI: 10.1007/978-3-642-60572-7_33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
7
|
Mintz CS, Arnold PI, Johnson W, Schultz DR. Antibody-independent binding of complement component C1q by Legionella pneumophila. Infect Immun 1995; 63:4939-43. [PMID: 7591161 PMCID: PMC173710 DOI: 10.1128/iai.63.12.4939-4943.1995] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Incubation of Legionella pneumophila Philadelphia 1 in normal human serum depleted of either classical-pathway component C1q or alternative-pathway component factor B resulted in activation of the complement system. Experiments focused on the role of the classical pathway in complement activation revealed that legionellae bound C1q independently of antibody. Purified preparations of L. pneumophila major outer membrane protein but not serogroup 1 lipopolysaccharide bound C1q independently of antibody. This suggests that antibody-independent binding of C1q by L. pneumophila can result in activation of the classical pathway in normal human serum and that major outer membrane protein may be a C1q acceptor on the L. pneumophila cell surface.
Collapse
Affiliation(s)
- C S Mintz
- Department of Microbiology and Immunology, University of Miami School of Medicine, Florida 33101, USA
| | | | | | | |
Collapse
|
8
|
Adler Y, Salozhin K, Le Tonqueze M, Shoenfeld Y, Youinou P. Anti-endothelial cell antibodies: a need for standardization. Lupus 1994; 3:77-84. [PMID: 7920618 DOI: 10.1177/096120339400300204] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Twenty years have passed since the original description of the anti-endothelial cell antibodies (AECA). It is widely acknowledged that the presence of circulating autoantibodies against endothelial cells surface antigens, found in a number of patients with connective tissue disease and vasculitis, is one of the driving mechanisms for the observed vascular injury and might be an important factor in initiating the pathogenesis of vascular abnormalities. AECA data regarding the prevalence, technical problems, presence with other autoantibodies, antigen distribution and immune endothelial cell injury associated with these autoantibodies, requires standardization for determining the precise pathophysiologic and immunologic role of anti-endothelial cell antibodies.
Collapse
Affiliation(s)
- Y Adler
- Laboratory of Immunology, Medical School, Brest, France
| | | | | | | | | |
Collapse
|
9
|
Beynon HL, Haskard DO, Davies KA, Haroutunian R, Walport MJ. Combinations of low concentrations of cytokines and acute agonists synergize in increasing the permeability of endothelial monolayers. Clin Exp Immunol 1993; 91:314-9. [PMID: 8428396 PMCID: PMC1554683 DOI: 10.1111/j.1365-2249.1993.tb05901.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The deposition of circulating immune reactants in blood vessels, an important event in the pathogenesis of certain types of vasculitis, requires an increase in permeability in the endothelial monolayer. An in vitro model to examine the integrity of endothelial cell monolayers and their response to inflammatory mediators has been developed. Human umbilical vein endothelial cells were grown to confluence on an FITC-labelled matrix and monolayer integrity was assessed by the exclusion of a 125I-anti-FITC antibody. Alteration in endothelial monolayer permeability was associated with an increase in uptake of 125I-anti-FITC antibody, expressed as a percentage of the maximal uptake of antibody on to FITC-matrix from which endothelial cells had been stripped. We determined the effects on endothelial monolayer permeability of acute agonists (thrombin and histamine), cytokines (tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-1 and IL-4) and combinations of acute agonists and cytokines. Addition of thrombin in concentrations ranging from 0.5 to 15 U/ml led to an increased uptake of 125I-anti-FITC antibody from 2% to 15% relative to unstimulated endothelium. For other agonists and cytokines the increases in permeability were: (i) histamine (50-400 pmol/ml) increased uptake 5-22%; (ii) TNF (12.5-100 ng/ml) increased uptake 2-12%; (iii) IFN-gamma (125-250 U/ml) increased uptake 1.5-3%. IL-1 beta (50-100 U/ml) and IL-4 (50-100 U/ml) had no effect. Synergistic interactions on endothelial monolayer permeability were seen with the following combinations: (i) IL-4 (100 U/ml) and TNF (12.5 ng/ml) uptake 11%; (ii) IL-4 (100 U/ml) and IFN-gamma (125 U/ml) uptake 6.5%; (iii) TNF (12.5 ng/ml) and IFN-gamma (125 ng/ml) uptake 7%; (iv) thrombin (0.5 U/ml) and histamine (50 pmol/ml) uptake 13.5%; and (v) TNF (12.5 ng/ml) and thrombin (0.5 U/ml) uptake 8.5%. These observations suggest that interactions between cytokines and acute inflammatory mediators such as thrombin and histamine may be important in determining whether immune complexes are deposited in vessel walls. This model system may now be useful for the further investigation in vitro of the mechanisms involved in the pathogenesis of immune complex-mediated vascular damage.
Collapse
Affiliation(s)
- H L Beynon
- Rheumatology Unit, RPMS, Hammersmith Hospital, London, UK
| | | | | | | | | |
Collapse
|
10
|
Abstract
Pulmonary endothelial cells form a continuous monolayer on the luminal surface of the lung vasculature. Until the mid-1970s, the pulmonary endothelium was felt to provide little more than a passive surface for the exchange of gases, water, macromolecules, and some cell traffic. Recent evidence indicates that the pulmonary endothelium is a metabolically active surface, which provides a regulatory interface for the continual processing of blood-borne vasoactive molecules, plays an active role in hemostasis and immunologic and inflammatory events, regulates vascular tone, and interacts with inflammatory cells and neighboring vascular cell types. These metabolic properties are both constitutive and capable of being induced in response to stimuli or injury. Virtually any agent that causes pulmonary endothelial cell injury will lead to impairments in the functional metabolic properties of these cells, resulting in alterations in hemodynamics, hemofluidity, permeability, gas exchange, and intercellular signaling. The net result in the lung is often the clinical picture of acute lung injury with respiratory distress, refractory hypoxemia, diffuse alveolar infiltrates, and respiratory failure.
Collapse
Affiliation(s)
- E R Block
- University of Florida College of Medicine, Gainesville
| |
Collapse
|
11
|
Bordin S, Smith M, Ghebrehiwet B, Oda D, Page RC. Smooth muscle and epithelial cells express specific binding sites for the C1q component of complement. CLINICAL IMMUNOLOGY AND IMMUNOPATHOLOGY 1992; 63:51-7. [PMID: 1591883 DOI: 10.1016/0090-1229(92)90093-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In injury and inflammation, interactions of complement C1q with C1q receptors may provide attachment sites for cell localization and tissue regeneration. Cultured smooth muscle cells (58%), epithelial cells (26%), and endothelial cells (25%) attach to C1q-coated surfaces, while only 6% of cultured B cells (Raji) attach. Endothelial and Raji cells express C1q receptors, but C1q receptors (C1qR) on smooth muscle cells and epithelial cells have not previously been demonstrated. Evidence is provided that smooth muscle cells express an average of 1.5 x 10(6) C1qR/cell (K alpha = 10(8) M-1) and that epithelial cells express an average of 0.7 x 10(6) C1qR/cell (K alpha = 1.4 x 10(8) M-1). Binding properties of C1qR, and immunoreactivity to anti-C1qR antibodies, are characterized. The antibodies specifically recognize a 67-kDa component of smooth muscle cell lysates and inhibit cell attachment to C1q substrates. We conclude that distribution of C1qR may be ubiquitous; binding properties, size, and antigenicity of various C1qR may be related, but adhesive function may be tissue specific.
Collapse
Affiliation(s)
- S Bordin
- Department of Periodontics, University of Washington, Seattle 98195
| | | | | | | | | |
Collapse
|
12
|
Shingu M, Yoshioka K, Nobunaga M, Motomatu T. C1q binding to human vascular smooth muscle cells mediates immune complex deposition and superoxide generation. Inflammation 1989; 13:561-9. [PMID: 2553603 DOI: 10.1007/bf00916762] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Evidence was obtained for the binding of C1q to the membrane of cultured vascular smooth muscle cells derived from human umbilical cord veins. C1q was fixed to the cell membrane at 4 degrees C, whereas it was ingested into the cytoplasm, as a cytoplasmic inclusion, when tested at 37 degrees C. The addition of C1q in advance inhibited the subsequent binding of C1q. Neither fibronectin nor laminin was detected on the cell membrane. Aggregated IgG bound to vascular smooth muscle cells in the case of preincubation with C1q at 4 degrees C, whereas aggregated IgG did not bind to the cells in the absence of C1q. The addition of C1q molecules to the cells in suspension enhanced superoxide generation by vascular smooth muscle cells. There was no effect of C1q on superoxide generation by the cells in monolayer. These results suggest that C1q binds on the membrane of vascular smooth muscle cells via its specific receptor that mediates immune complex binding to the cells and superoxide generation. These properties elucidate the mechanisms by which circulating immune complexes deposit in the vascular wall, and subsequent degradation of tissue components surrounding vascular smooth muscle cells occurs through oxidative burst of the cells.
Collapse
Affiliation(s)
- M Shingu
- Department of Internal Medicine, Kyushu University, Beppu, Japan
| | | | | | | |
Collapse
|
13
|
|
14
|
Ryan US, Schultz DR, Goodwin JD, Vann JM, Selvaraj MP, Hart MA. Role of C1q in phagocytosis of Salmonella minnesota by pulmonary endothelial cells. Infect Immun 1989; 57:1356-62. [PMID: 2540090 PMCID: PMC313282 DOI: 10.1128/iai.57.5.1356-1362.1989] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The Re mutant of Salmonella minnesota adheres in much greater numbers than the wild type to endothelial cells derived from the bovine pulmonary artery. Since the Re mutant is distinguished from wild-type S. minnesota by its ability to bind C1q and since endothelial cells possess receptors for C1q, we examined the role of C1q in the phagocytosis of the S. minnesota Re mutant. First, preincubating endothelial cells with C1q-enriched medium resulted in increased adherence of the Re mutant (17.9 x 10(4) versus 6.6 x 10(4]. Second, preincubating the Re mutant with C1q-enriched medium resulted in increased numbers of adherent bacteria (62.1 x 10(4) versus 6.6 x 10(4]. Preincubation of both endothelial cells and bacteria with C1q-enriched medium resulted in increased adherence above control levels but less adherence than when either cells or bacteria were preincubated separately in C1q-enriched medium. If serum depleted of C1q was used for preincubation of endothelial cells or bacteria, adherence was reduced below control levels. Thus, C1q plays an important role in the initial steps (recognition, binding, and ingestion) of phagocytosis. Next, the role of C1q was investigated in the respiratory burst response. Levels of superoxide anion released from endothelial cells 15 min after phagocytosis of the Re mutant (100 bacteria per endothelial cell) were assayed by measurement of the superoxide dismutase-inhibitable reduction of ferricytochrome c. Superoxide anion release was increased during phagocytosis of the Re mutant (35 nmol of O2- per 3 x 10(6) endothelial cells) and was also elevated above control values by incubation with soluble C1q (10 nmol of O2- per 3 x 10(6) endothelial cells). These results indicate a role for C1q in both the ingestion and the response of endothelial cells to the S. minnesota Re mutant.
Collapse
Affiliation(s)
- U S Ryan
- Department of Medicine, University of Miami School of Medicine, Florida 33101
| | | | | | | | | | | |
Collapse
|
15
|
Abstract
The presence of circulating immune complexes have been described in many different human disease states but the significance of their presence has always been a subject for debate. Improvements in the methods of detecting immune complexes have demonstrated a wide degree of heterogeneity, which accounts for the difficulty in obtaining accurate and reproducible measurements, even in the same individual. Techniques for isolating individual complexes, characterizing their pathophysiological properties, and biochemically analyzing the nature of the complexed antigen are now being used to provide data that is helping to clarify the role of immune complexes in the pathogenesis of disease. In addition, such studies are also providing data which is proving that immune complexes have a potential role in immune regulation.
Collapse
Affiliation(s)
- T M Phillips
- Department of Immunochemistry and Medicine, George Washington University Medical Center, Washington, D.C
| |
Collapse
|
16
|
Martin H, Loos M. Guinea pig macrophages synthesize a low molecular weight form of C1q with affinity for the C1r2C1s2-complex but which does not bind to Fc in immunoglobulin aggregates. Mol Immunol 1988; 25:1231-7. [PMID: 2853293 DOI: 10.1016/0161-5890(88)90037-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Biosynthetically labelled C1q secreted by guinea pig peritoneal macrophages was analysed by sedimentation through sucrose gradients followed by SDS-PAGE. In addition to the haemolytically active C1q of mol. wt 460,000 Da a low mol. wt (LMW) form of C1q was identified which had no detectable affinity for Fc of aggregated immunoglobulin, but which retained the ability to associate with the C1r2s2-complex. This LMW-C1q was covalently associated with two additional polypeptides of mol. wt 46 and 50 kDa.
Collapse
Affiliation(s)
- H Martin
- Institute für Medizinische Mikrobiologie, Augustusplatz/Hochhaus, Mainz, F.R.G
| | | |
Collapse
|
17
|
Daha MR, Miltenburg AM, Hiemstra PS, Klar-Mohamad N, Van Es LA, Van Hinsbergh VW. The complement subcomponent C1q mediates binding of immune complexes and aggregates to endothelial cells in vitro. Eur J Immunol 1988; 18:783-7. [PMID: 3259929 DOI: 10.1002/eji.1830180519] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The present studies were initiated to investigate whether soluble immune complexes, upon interaction with complement, can bind to endothelial cells. Human umbilical vein endothelial cells (HUVE) were incubated with purified human 125I-labeled C1q at 4 degrees C in RPMI-0.5% bovine serum albumin and assayed for binding. Optimal binding of 125I-labeled C1q to HUVE was reached within 2 h, and saturation of binding was found at concentrations of 5 micrograms/well input. The binding of 125I-labeled C1q was inhibitable with unlabeled C1q and by the collagenous region of pepsin-cleaved C1q. No inhibition was observed with the globular heads of C1q, suggesting that C1q binds to HUVE via the collagenous region of C1q. When HUVE were first reacted with various concentrations of C1q, washed and subsequently incubated with 125I-labeled aggregated human IgM (AIgM), binding of 125I-labeled AIgM to HUVE occurred depending on the dose of C1q. Only those aggregates of IgM which react with C1q in a solid-phase C1q binding assay were able to bind to HUVE presensitized with C1q. In addition it was shown that C1q mediated binding of aggregated IgG to HUVE. Furthermore, immune complexes (IC), that were prepared with bovine thyroglobulin (BTg) and rabbit anti-BTg, bound to C1q-preincubated HUVE. These studies suggest that localization of IC on endothelium can be enhanced following interaction of the IC with complement.
Collapse
Affiliation(s)
- M R Daha
- Department of Nephrology, University Hospital Leiden, The Netherlands
| | | | | | | | | | | |
Collapse
|
18
|
Affiliation(s)
- U S Ryan
- School of Medicine, University of Miami, Florida 33101
| |
Collapse
|
19
|
Drenk F, Sander U, Alheid U, Serbin A, Deicher H. Mouse monoclonal antibodies specific for endothelial cells. Mol Cell Biochem 1987; 76:67-73. [PMID: 3627115 DOI: 10.1007/bf00219399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Balb/c mice were immunized with a human endothelial cell pool. Spleen cells were then fused with a NS-O hybridoma cell line. A number of hybridomas secreted antibodies that reacted with the immunizing endothelial cell pool as well as with every other tested umbilical cord vein derived human endothelial cell. These monoclonal antibodies also stained pig, rabbit and ox aortic endothelial cells indicating their specificity for this cell type. Five of 16 monoclonal antibodies additionally reacted with human fibroblasts (HFIB). The produced monoclonal antibodies did not recognize FVIIIR:AG or MHC determinants. They can therefore be regarded as additional and reliable markers for endothelial cells in vitro.
Collapse
|