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Biomedical subjects

D B Cines

Publications and source records attributed to D B Cines.

At least 91 records · Page 5Linked to original sources
PubMed1986

Antibody and immune complexes induce tissue factor production by human endothelial cells.

Patients with systemic lupus erythematosus (SLE) have an increased incidence of arterial and venous thromboses. The mechanism by which thromboses develop in these patients is unknown. We had previously observed that the sera of patients with SLE contain antibodies and immune complexes that can bind to endothelial cells. Because endothelial cells can synthesize tissue factor, a potent activator of coagulation, we studied the effect of IgG complexes and sera from patients with SLE on the production of tissue factor by these cells. Human umbilical venous endothelial cells incubated with heat-aggregated IgG (HA-IgG) (0.5 to 4.0 mg) elaborate procoagulant activity in a dose-dependent manner. All procoagulant activity was found in the particulate cell fraction, and none was secreted into the medium. Maximum expression of procoagulant activity required 6 to 8 hr, and its production was totally inhibited by the addition of cyclohexamide or actinomycin D. The presence of gel-filtered platelets augmented production of procoagulant activity by endothelial cells stimulated by HA-IgG. Endothelial cell procoagulant activity was not inactivated by diisofluoropropylphosphate, required the presence of Factor VII for its expression, and was neutralized by a specific anti-tissue factor antibody. Endothelial cells incubated with sera from 14 of 16 patients with SLE produced increased amounts of tissue factor compared with 21 normal sera (p less than 0.025). Fractions of two SLE sera containing monomeric IgG, IgA, or IgM, as well as fractions containing IgG complexes, each stimulated endothelial cells to produce more tissue factor than similar fractions prepared from two normal sera. These studies demonstrate that endothelial cells will produce the procoagulant tissue factor after exposure to anti-endothelial cell antibodies or IgG-containing immune complexes. The production of tissue factor by endothelial cells at sites of immune vascular injury may play a role in the development of thromboses in patients with SLE.

Antibodies↗
PubMed1986

In vitro binding of an IgE protein to human platelets.

Bronchoconstriction in extrinsic asthma is initiated by mediators released from IgE-sensitized leukocytes after contact with polyvalent antigen. Because platelets also contain soluble mediators that can cause bronchoconstriction, platelet activation and release of the contents of platelet granules may play a role in IgE-mediated responses under some circumstances. We therefore sought to determine if platelets are capable of binding IgE and if cross-linking this cell-bound IgE initiates secretion of platelet granule contents. Platelets from 10 normal donors were studied by using automated fluorescence analysis and fluorescence microscopy. We detected binding of a purified myeloma IgE protein to 24.1 +/- 9.6% (mean +/- 2 SD) of the gel-filtered platelets from these normal individuals. Although we could detect the binding of IgE and anti-IgE to a minority of cells, every normal individual had a population of platelets that bound IgE. The amount of IgE that bound to normal platelets appeared to be distributed heterogeneously among the IgE-positive platelet population. Platelets from two individuals with type II Glanzmann's thrombasthenia bound normal amounts of heat-aggregated IgG, but less than 3% of the platelets bound detectable IgE. Moreover, a combination of monoclonal antibodies to glycoproteins IIb and IIIa inhibited the binding of the IgE protein to normal platelets but did not affect the binding of aggregated IgG. Thus, the binding of IgE to human platelets appeared to require the presence of the glycoprotein IIb-IIIa complex. Binding of monomeric IgE to platelets, by itself, did not initiate either platelet aggregation or release of 14C-serotonin. However, both aggregation and secretion of serotonin followed the addition of anti-IgE to IgE-sensitized platelets. These studies indicate that human platelets can bind an IgE myeloma protein in vitro and that cross-linking of surface-bound IgE with anti-IgE initiates aggregation and secretion. If platelets have a similar capacity to bind normal IgE in vivo, it is possible that platelets may participate directly in several atopic or inflammatory disorders in man mediated by this class of antibody.

Antibody Specificity↗
PubMed1985

Isolation and characterization of monoclonal antibodies reactive with endothelial cells.

Monoclonal antibodies were generated to antigens on cultured human umbilical vein endothelial cells. Spleen cells from BALB/c mice, immunized with low passage cultures of human umbilical vein endothelial cells, were fused with the non-secretory myeloma line, P3 x 63Ag 8.653. Hybridoma supernatants were screened for the desired immunological reactivity using ELISA binding assays. Hybridomas secreting antibodies reacting with the immunizing endothelial cells, but not with peripheral blood mononuclear cells, were cloned by limiting dilution and three stable clones were chosen for study. Further testing by ELISA revealed that each antibody displayed a unique pattern of reactivity. One antibody, 14E5, reacted with the macrophage-like cell line DHL-2, cultured macrophages derived from peripheral blood monocytes, and macrophages derived from malignant effusions. The antibody failed to react with fibroblasts or bovine endothelial cells. The second antibody, 12C6, reacted with human and primate fibroblasts and endothelial cells derived from bovine arteries, but not with mature macrophages. The third clone, 10B9, reacted only with the immunizing endothelial cells and the immature-macrophage line U-937. All three antibodies failed to react with long-term human B or T lymphoblastoid cell lines, leukemic cell lines, or murine macrophage lines. None of the antibodies reacted with a battery of human epithelial derived cell lines or primary cultures of human epithelial cells. Indirect immunofluorescence assays revealed that the antigens were expressed on the cell surface. These antibodies should prove useful as differentiation markers of human endothelial cells and in studies of endothelial cell function.

Antibodies, Monoclonal↗
PubMed1985

Platelet antibodies of the IgM class in immune thrombocytopenic purpura.

The clinical course and response to therapy of patients with immune thrombocytopenic purpura (ITP) are not completely determined by the level of IgG present on the platelet surface. It is possible that antibodies of other immunoglobulin classes also play a role in platelet destruction in some of these patients. Therefore, we studied 175 patients with ITP for the presence of IgM anti-platelet antibodies using radiolabeled polyclonal or monoclonal anti-IgM. We observed that 57% of patients with clinical ITP had increased levels of IgM on their platelets, compared with normal controls and patients with thrombocytopenia who did not have ITP (less than 10%), (P less than 0.01). We obtained similar results using either radiolabeled polyclonal or monoclonal anti-IgM, reagents whose integrity was first characterized using erythrocytes coated with defined amounts of IgM antibody. Among patients with increased platelet-IgM there was a significant correlation both with the presence of increased platelet-C3 as well as the amount of platelet-C3 (P less than 0.01, r = 0.53). We demonstrated the presence of warm-reacting IgM anti-platelet antibodies in the plasma of two of these patients who were further studied. The isolated IgM fraction from these two plasmas was able to activate complement and place 3H-C3 on normal platelets. These studies demonstrate the presence of warm-reacting IgM anti-platelet antibodies in some patients with ITP. They suggest that the binding of complement to platelets by IgM antibodies may initiate platelet clearance as well as enhance the effect of IgG antibodies in ITP.

Autoantibodies↗
PubMed1985

Viral infection of vascular endothelial cells alters production of colony-stimulating activity.

Viral infections in humans are frequently associated with granulocytopenia and/or granulocytosis. Such changes in myelopoiesis could result from infection of the granulocyte-macrophage colony-forming cell (CFC-GM) or changes in the production of colony-stimulating activity (CSA). Endothelial cells are a known source of CSA and may be transiently or persistently infected during a number of viral infections, including infection with herpes simplex virus type I (HSV-I) and measles virus. Therefore, we examined the effect of endothelial cell infection with these two viruses on the production of CSA. Uninfected passaged endothelial cells produce CSA when stimulated by the continual presence of a factor present in medium conditioned by peripheral blood monocytes (MCM). Within 4 h of infection with HSV-I, endothelial cells no longer produced CSA in response to MCM. In contrast, measles virus infection induced CSA production by passaged endothelial cells even in the absence of MCM. Measles virus-induced CSA production was maximal at 24 h and required the presence of live virus within the endothelial cells. The effects of HSV-I and measles virus on CSA production were not dependent on alterations in the production of alpha- or gamma-interferon by the infected endothelial cells. Infection with HSV-I did not stimulate endothelial cells to release any detectable interferon. In contrast, the supernatants of the measles-infected cells contained only beta-interferon, a known inhibitor of CFC-GM development. These studies suggest that CSA production by endothelial cells is directly altered by infection with HSV-I and measles virus. An alteration in CSA production might contribute to changes in myelopoiesis that frequently accompany viral infection in humans.

Cells, Cultured↗
PubMed1985

Danazol therapy in myelodysplasia.

Platelet-associated IgG was markedly elevated in three patients with myelodysplasia and severe thrombocytopenia that had become refractory to platelet transfusions. The patients were treated with danazol because of its efficacy in treating immune thrombocytopenic purpura where platelet destruction is primarily mediated by IgG autoantibodies. After danazol therapy, the platelet counts of each patient rose and clinical bleeding stopped, and a decline in hemolysis was seen in two patients. Danazol probably impeded the peripheral clearance of cells by macrophages; however, a beneficial effect of danazol on hematopoiesis cannot be excluded.

Aged↗
PubMed1985

Platelet kinetics in patients with idiopathic thrombocytopenic purpura and moderate thrombocytopenia.

We studied ten normal subjects and 20 patients with stable, untreated idiopathic thrombocytopenic purpura (ITP) and platelet counts in the range of 35,000 to 110,000/microL. The diagnosis was made by clinical criteria. Platelet-associated IgG was increased in all nine of the nine patients studied. Autologous platelets were labeled with chromium 51 and reinfused for measurement of mean cell life and platelet production rate. Mean cell life was calculated by two methods, weighted mean and multiple hit, with excellent agreement between the two. As expected, mean cell life was significantly reduced in ITP patients as compared to the normal subjects (2.9 days v. 8.0 days, P less than .001). However, mean platelet production rates in ITP patients and normal subjects, 3.5 and 3.8 X 10(9) platelets/k/d respectively, were not significantly different. Platelet production rate was above and below the normal range (2 to 5.6 X 10(9) platelets/k/d) in two and four patients, respectively. We conclude that the rate of platelet production is not increased in most patients with ITP who have platelet counts greater than 35,000/microL. We did find that platelet size was increased in eight of the 12 patients in whom it was measured, including two of the patients with low platelet production.

Adolescent↗
PubMed1984

Infection of human endothelial cells by human T-cell leukemia virus type I.

The effects of the human T-cell leukemia virus type I (HTLV-I) on cultured human endothelial cells were evaluated. Coculture of endothelial monolayers with either irradiated HTLV-producing lymphocytes or cell-free virus resulted in the production of multinucleated syncytia. The development of syncytia was inhibited by sera from patients with adult T-cell leukemia/lymphoma (ATLL). HTLV antigens were present on endothelial syncytia passaged in culture for greater than 3 months as detected by an anti-p19 monoclonal antibody, which detects a core protein of HTLV-I, and by ATLL sera. Moreover, these HTLV-infected endothelial cells were then able to infect and transform normal cord blood T lymphocytes with HTLV. These studies demonstrate that human endothelial cells are susceptible to productive HTLV-I infection in vitro and may have relevance for the spectrum of human disease associated with this family of retroviruses.

Antibodies, Monoclonal↗
PubMed1984

Presence of complement-fixing anti-endothelial cell antibodies in systemic lupus erythematosus.

Vasculitis in systemic lupus erythematosus (SLE) is associated with the deposition of IgG and complement in blood vessel walls. However, it is not known whether immune injury to endothelial cells is a part of this process. Therefore, we used a solid phase radioimmunoassay to study the ability of IgG from normal human sera and sera from patients with SLE to bind to endothelial cells. In this assay, cultured human umbilical venous endothelial cells were sequentially incubated with normal or SLE sera, goat anti-human IgG, and 125I-labeled staphylococcal protein A (*SPA). After exposure to normal sera, 2.5 +/- 0.5% (mean +/- SD) of the added *SPA bound to the cells, whereas after exposure to SLE sera 13.8 +/- 7.6% of the added *SPA bound to these cells. This difference in binding was highly significant (P less than 0.001). Binding was partially reduced when SLE sera were preincubated with B-lymphocytes or monocytes, but not after exposure to erythrocytes, platelets, or T lymphocytes. Incubation of endothelial cells with the 7S fraction of SLE sera or with the F(ab')2 fragment of SLE-IgG resulted in the deposition of greater than 80% as much IgG as was deposited on endothelial cells by whole serum. However, since higher molecular weight fractions (greater than 7S) of SLE sera were also active, we tested the capacity of endothelial cells to bind IgG complexes. Endothelial cells bound heat-aggregated IgG (HA-IgG) in a saturable manner at one log concentration below the binding of normal monomeric IgG. Binding of HA-IgG to endothelial cells was markedly enhanced by preincubation with a serum source of complement. Both HA-IgG and SLE-IgG also bound to freshly obtained endothelial cells in suspension, as detected by automated fluorescence flow cytometry. Binding of SLE-IgG and HA-IgG to endothelium initiated complement activation, deposition of the third component of complement, and disruption of the monolayer. In addition, SLE-IgG and HA-IgG caused endothelial cells to secrete prostacyclin and caused the adherence of platelets, confirmed by scanning electron microscopy. These studies demonstrate that IgG anti-endothelial antibodies are present in the sera of patients with active SLE. These sera may also contain IgG complexes that are capable of binding to endothelial cells. The association of IgG and complement with endothelial cells may initiate vascular injury in SLE and other human disorders.

Antibody Specificity↗
PubMed1983

Functional consequence of variation in melanoma antigen expression.

Melanoma cells have been shown to express melanoma-associated antigens and, in many cases, the histocompatibility antigen, HLA-DR. We questioned whether the expression of these antigens was quantitatively altered during the serial passage of melanoma cells in culture. Therefore, we measured the binding of monoclonal antibodies specific for a melanoma-specific antigen and the HLA-DR antigen to melanoma cells from serial passages. Three cell lines were studied. We found that although both the melanoma-associated antigen and the HLA-DR antigen were qualitatively conserved, significant quantitative differences were seen. To study the functional consequences of these differences, we used fluorescence-activated cell sorting to create DR-enriched and DR-depleted populations from a single melanoma cell line heterogeneous for DR expression. We found that the proliferation of allogeneic T cells (measured by the 3H-TdR uptake) cultured with the DR-enriched and -depleted melanoma cell populations was directly related to the amount of the HLA-DR antigen expressed. These results indicate that in performance of experiments using melanoma cell lines quantitative assessment of antigenic expression is important, particularly if the function of a specific antigen is under examination. Further, our data clearly identify the HLA-DR antigen on melanoma cells as a participant in allogeneic lymphocyte stimulation.

Antibodies, Monoclonal↗
PubMed1983

Antibodies reactive with surface membranes of cellular elements in the blood.

Autoreactive antibodies or immune complexes may accelerate clearance of mature erythrocytes, leukocytes, and platelets from the circulation in patients with rheumatologic and immunologic disorders. The most compelling evidence for immune injury to hematopoietic cells exists in patients with systemic lupus erythematosus and patients with Felty's syndrome and its variants. These disorders may also cause tissue inflammation, which in turn commonly results in underproduction of erythrocytes and development of thrombocytosis. However, recent evidence indicates that underproduction of hematopoietic cells may also result from immune injury to cellular elements in the bone marrow. In many laboratories, sensitive techniques are now clinically available for the detection of cell-associated immunoglobulin and complement. These assays have helped confirm the role of antibody in the pathogenesis of autoimmune hemolytic anemia and idiopathic thrombocytopenic purpura. However, recent data indicate that there is probably a continuum between the amount of immunoglobulin and complement found on normal cells and that found in a variety of disease states. In several of these disorders, additional evidence will be required to establish that the increase in cell-bound immunoglobulin leads to a decrease in the life-span of the cell. In order to provide significant help to the clinician managing an individual patient, these serologic tests must be capable of identifying the portion of the cell-associated protein actually involved in the destructive process. The availability of monoclonal reagents capable of identifying restricted regions on cell-bound immunoglobulin may help identify molecules bound specifically as antibody and may help identify the antigens involved in autoimmune disorders.

Anemia, Hemolytic, Autoimmune↗
PubMed1983

Inhibition of fibrinogen binding to stimulated human platelets by a monoclonal antibody.

Fibrinogen binding to receptors on stimulated platelets is a prerequisite for platelet aggregation. To gain further insight into the role of fibrinogen in platelet aggregation and to identify the platelet fibrinogen receptor, we developed a monoclonal anti-platelet antibody that inhibited platelet aggregation. The purified antibody, designated A2A9, inhibited platelet aggregation stimulated by 10 microM ADP, 10 microM epinephrine, and thrombin at 1 unit/ml without inhibiting platelet shape change or platelet secretion. A2A9 was also a competitive inhibitor of fibrinogen binding to ADP-stimulated platelets. Fifty percent inhibition of fibrinogen binding occurred at 65 nM A2A9. Direct binding studies using radiolabeled A2A9 demonstrated 47,000 A2A9 binding sites on unstimulated platelets, with a dissociation constant of 60 nM. Platelets from two individuals with Glanzmann thrombasthenia bound essentially no A2A9. Therefore, these data support the hypothesis that receptor-bound fibrinogen mediates platelet aggregation. In order to identify the platelet fibrinogen receptor, A2A9 immobilized on agarose was used for affinity chromatography. Two platelet polypeptides with Mr = 140,000 and 93,000 were recovered from the immobilized A2A9. After disulfide reduction, these Mr values were altered to 125,000 and 116,000. The smaller polypeptide was also found to contain the PlA1 antigen. These data localize the epitope recognized by A2A9 to the platelet membrane glycoprotein IIb-IIIa complex and suggest that this complex forms the physiologic platelet fibrinogen receptor.

Adenosine Diphosphate↗
PubMed1983

Effect of antiplatelet antibody on platelet shape change, volume, and morphology.

We extended our studies of the effect of antibody on human platelets. Monomeric immunoglobulin G (IgG) (rabbit) antiplatelet antibody was interacted with human platelets in the absence of complement and the early morphological changes monitored. Platelet shape change, assessed by a rheooptical approach, was noted within 20 s and was proportional to antibody concentration. Antiplatelet antibody-induced shape change was also accompanied by a change in apparent platelet volume, as measured in the resistive particle counter. Scanning and transmission electron microscopy confirmed a disk-to-sphere transformation associated with the formation of bulbous, short surface projections or pseudopodia. In contrast, ADP-induced disk-to-sphere transformation was associated with the development of long, thin filopodia emanating from the platelet. These specific effects of antiplatelet antibody may result in altered platelet function.

Adenosine Diphosphate↗
PubMed1982

Identification of the fibrinogen receptor on human platelets by photoaffinity labeling.

Fibrinogen binding to receptors on stimulated platelets is a prerequisite for platelet aggregation. In order to identify the platelet fibrinogen receptor, we modified fibrinogen with the photoreactive, heterobifunctional cross-linking reagent methyl 4-azidobenzoimidate (MABI). MABI-fibrinogen was fully clottable and able to support platelet aggregation. To photoaffinity label the fibrinogen receptor, gel-filtered human platelets were incubated at 37 degrees C in the dark with 200 micrograms/ml of MABI-fibrinogen, 10 microM ADP, and 0.5 mM calcium. Irradiation of these platelets with ultraviolet light resulted in the incorporation of MABI-fibrinogen into the platelet surface. Incorporation could be prevented by excess native fibrinogen suggesting that MABI-fibrinogen had interacted with the fibrinogen receptor before photolysis. Examination of the irradiated platelets by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the photoactivated MABI-fibrinogen had been incorporated into a 105,000 molecular weight membrane polypeptide that also contained the PlA1 antigen. Thus, this polypeptide has the characteristics of the membrane glycoprotein IIIa. Previous studies have shown that thrombasthenic platelets lack this glycoprotein and fail to bind fibrinogen after stimulation by ADP. Consequently, our data suggest that glycoprotein IIIa constitutes at least one component of the platelet fibrinogen receptor.

Affinity Labels↗
PubMed1982

Immune thrombocytopenic purpura and pregnancy.

Neonatal thrombocytopenia is a potentially life-threatening complication of immune thrombocytopenic purpura (ITP). We followed 23 pregnant women who had either a history of ITP (11 women) or clinically active disease (12 women) to delineate the factors responsible for neonatal thrombocytopenia. No relation was observed between maternal and neonatal platelet counts (P greater than 0.5). Eleven women delivered thrombocytopenic children; antiplatelet antibodies were detectable in each mother, including five who were in clinical remission at delivery. The level of platelet-associated IgG in the mothers did not identify the neonates at risk for thrombocytopenia (P greater than 0.05). However, the level of maternal circulating antiplatelet antibody correlated with both the presence and the extent of neonatal thrombocytopenia (P less than 0.005). A discrepancy between maternal platelet count and maternal antibody level may be especially notable in mothers treated with steroids or splenectomy. Monitoring the level of circulating antiplatelet antibody may help in identifying and managing pregnant women with ITP at risk of delivering neonates with serious thrombocytopenia.

Adrenal Cortex Hormones↗
PubMed1982

Fc and C3 receptors induced by herpes simplex virus on cultured human endothelial cells.

The mechanism by which immune complexes deposit in vascular tissue is uncertain. Several human viruses, including herpes simplex virus, have recently been demonstrated to replicate in human endothelial cells. Such viruses may injure vascular tissue and could play a role in the pathogenesis of immune complex deposition. Therefore, we studied the expression of receptors for immune complexes containing IgG and C3 on endothelial cells after infection with herpes simplex virus type I.Human umbilical vein endothelial cells were incubated with (51)Cr-labeled sheep erythrocytes sensitized with IgG, IgM, or IgM plus complement. Preferential binding of IgG or complement-coated erythrocytes to uninfected endothelial monolayers was not observed. In contrast, significant binding of erythrocytes coated with IgG or IgM plus complement was observed after viral infection. Phase-contrast and scanning electron microscopy demonstrated erythrocyte adherence around the infected endothelial cells in a rosette pattern. Binding of IgG-coated erythrocytes was fully inhibited by Fc (0.31 mg/ml) but not Fab' fragments of nonimmune IgG. Binding of complement-coated cells was unaffected by the presence of IgG (1 mg/ml). With purified individual components, binding of complement-coated erythrocytes depended on the presence and was proportional to the concentration of C3. Binding of IgG-or C3-coated cells was detected beginning 4 h after infection. These studies indicate that herpes simplex virus type I infection can induce IgG and C3 receptors on human endothelial cells. These receptors may promote the deposition of immune complexes in vascular tissue after certain viral infections.

Culture Techniques↗
PubMed1982

Granulocyte-associated IgG in neutropenic disorders.

We applied a radiolabeled antiglobulin test to a study of patients with a variety of neutropenic disorders. After defining the nature of the interaction of radiolabeled anti-IgG with the neutrophil, we studied 16 patients with neutropenia of uncertain etiology and adequate bone marrow granulocyte precursors. Twelve of these 16 patients had increased neutrophil-associated IgG (PMN-IgG). Patients with the highest levels of PMN-IgG had the lowest neutrophil counts. The majority of patients with neutropenia and increased PMN-IgG had an underlying immunologic disorder that included immune thrombocytopenic purpura in 5 patients and autoimmune hemolytic anemia in 1 patient. In some patients, elevated PMN-IgG preceded other evidence for immunologic disease. The direct antiglobulin test helped to distinguish neutropenic patients with increased PMN-IgG both from patients with neutropenia due to a known nonimmune disorder and from nonneutropenic patients with rheumatoid arthritis or systemic lupus erythematosis. Each of four patients with increased neutrophil-associated IgG treated with systemic corticosteroids responded clinically with an associated fall in neutrophil IgG and a rise in the circulating neutrophil count. The radiolabeled antiglobulin test appears useful in defining a subpopulation of patients with neutropenia due to an underlying immunologic disorder.

Adrenal Cortex Hormones↗