Levels Of Anti-endothelial Cell Antibodies Research Articles

Immunological characterization of anti-endothelial cell antibodies induced by cytomegalovirus infection.

We have previously shown that the levels of anti-endothelial cell antibodies (AECA) determined by an enzyme immunoassay are elevated during cytomegalovirus (CMV) infection in cardiac and renal transplant recipients. In a separate study, high levels of AECA are associated with higher frequency of humoral allograft rejection (AR), chronic AR and lower 2 year allograft survival in cardiac transplant recipients. These results suggests that high levels of AECA produced during CMV infection may have a pathogenic role or be a risk factor for humoral AR, chronic AR and decreased allograft survival. Here we examined the reactivity of AECA against endothelial cells and other tissues to further characterize AECA induced by CMV infection. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blot analysis was performed. The number and intensity of bands reactive with human umbilical vein ECs (HUVECs) increased during and after CMV infection. AECA(+) plasma reacted with multiple antigens expressed not only on endothelial cells but also on human fibroblasts, keratinocytes, platelets (PLs), peripheral blood mononuclear cells (PBMCs), Raji cells and THP-1 cells. Each individual's AECA(+) plasma showed different patterns of reactivity against these cells, whereas each plasma showed similar patterns of reactivity against ECs, PLs or peripheral blood mononuclear cells obtained from different individuals. AECA(+) plasma also showed a similar pattern of reactivity against HUVECs pretreated with/without interferon-gamma/tumor necrosis factor-alpha. The reactivity of preabsorbed sera with PLs significantly decreased against most reactive antigens expressed on PLs and other cell types. (1) Antibodies induced by CMV infection are not specific to endothelial cells and appear to react with multiple cell types, (2) AECA (+) plasma react with multiple antigens expressed on various cell types that are primarily constitutively expressed on these cells and are not individual specific, (3) CMV-induced antibodies in AECA (+) plasma are primarily autoantibodies. These results suggest that the elevated AECA levels seen in CMV-infected transplant recipients may represent a polyclonal activation of humoral immune responses induced by CMV, which is of uncertain pathogenic significance.

Anti-endothelial cell antibodies in the sera of hyperprolactinemic women.

Prolactin (PRL) is closely associated with autoimmune diseases in animal models and humans, and several disease-related autoantibodies were reported in increased titers in patients with hyperprolactinemia (HPRL). We studied the presence of anti-endothelial cell antibodies (AECA) and other autoantibodies in sera of female patients with HPRL. Sera from 25 HPRL patients and 10 healthy female controls were tested for AECA (against both macrovascular and microvascular endothelial cell antigens), anti-dsDNA, and anti-cardiolipin (anti-CL) using ELISA. Sera were considered positive for the autoantibody when the optical density (OD) value was more than 3 s.d. above the mean of the OD in normal controls. Sera from 13 patients were obtained repeatedly during dopaminergic anti-PRL treatment, to relate PRL level or anti-PRL treatment with the autoantibody levels. Elevated micro and/or macrovascular AECA were observed in sera from 19/25 patients (76%). Elevated titers of anti-CL Abs, all beta2-GPI-dependent, and low levels of anti-dsDNA antibodies (Abs) were also observed in the HPRL patients. Inhibition studies showed that the affinity purified AECAs bound the endothelial cell (EC) antigens in a dose-dependent manner. Titers of AECA as well as anti-DNA and anti-CL autoantibodies did not correlate with PRL level nor with the use or duration of anti-PRL treatment. None of the HPRL patients presented clinical manifestations of autoimmune disease. We conclude that elevated levels of AECA as well as anti-DNA and anti-CL autoantibodies are frequent in hyperprolactinemia. Our results further support the association of PRL and autoimmunity, and may point to a relationship between AECA-associated diseases and HRPL. The presence of autoantibodies in patients with HPRL might portend an increased risk for future development of autoimmune disease.

A study of coagulation and anti-endothelial antibodies in idiopathic livedo reticularis.

Livedo reticularis is associated with collagen vascular diseases and other vaso-occlusive disorders in a substantial number of cases. In the remaining cases the cause of livedo reticularis is still unknown. (i.e., idiopathic). We sought to determine a possible causal relationship between idiopathic livedo reticularis and autoimmune factors associated with the coagulation system, including antiendothelial cell antibodies. Nine patients with idiopathic livedo reticularis were studied. All patients were found to have normal platelet count, fibrinogen levels, and prothrombin and activated partial thromboplastin times, as well as negative results for Venereal Disease Research Laboratory and D-timer tests. Anticoagulant activity was detected in 2 patients: one had positive results of thromboplastin titration index and Russell's viper venom test, as well as increased levels of anticardiolipin antibodies and anti-endothelial cell antibodies; the other has positive thromboplastin titration index, mildly increased levels of anti-endothelial cell antibodies, and markedly increased levels of antinuclear antibodies. A third patient had mildly increased levels of anti-endothelial cell antibodies alone, and a fourth patient had mildly increased levels of antinuclear antibodies only. The clinical outcome was uneventful in all of the patients during an 18-month follow-up period. These findings suggest involvement of autoimmune factors associated with the coagulation system in some patients with idiopathic livedo reticularis, whose clinical significance remains to be determined.

A Prospective Study on Anti–endothelial Cell Antibodies in Patients with Systemic Lupus Erythematosus

IgG anti–endothelial cell antibodies (AECA) were detected in 48.5% of patients with active systemic lupus erythematosus (SLE) and in 7% of patients during remission and were associated with the development of diffuse proliferative lupus nephritis. Sixteen AECA-positive patients were prospectively studied for 25.2 ± 2.9 months. Serial AECA levels correlated with disease activity in 10 (62.5%) patients. Seven (43.8%) of 16 patients remained AECA positive during clinical remission. Among four episodes of disease exacerbation and 16 instances of clinical improvement, 85% (17 episodes) were accompanied by corresponding changes in the level of AECA, while corresponding changes in C3, anti–nuclear antibodies, and anti–double-stranded DNA antibodies were noted in 60, 60, and 80% of cases, respectively (p= not significant). AECA served as the only serologic marker of altered disease activity in five episodes, when C3, ANA, and anti–double-stranded DNA levels remained unaltered. We conclude that the level of AECA can serve as a marker of disease activity in SLE and that serial monitoring of AECA can complement other serologic parameters in the management of patients.

Endothelium-derived haemostatic factors and the antiphospholipid syndrome.

The cause of thrombosis in the antiphospholipid syndrome (APS) is unknown. There have been reports of abnormalities in the antigenic levels or activity of endothelium-derived haemostatic factors, such as tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1); however the data from these studies are conflicting. We studied plasma from nine patients with APS; seven of them had a history of thrombosis, and three had systemic lupus erythematosus (SLE). We also studied nine matched control patients who had SLE without APS, and 14 healthy individuals. We measured t-PA, von Willebrand factor (vWF), anticardiolipin antibody (ACA) and anti-endothelial cell antibody (AECA) levels by enzyme-linked immunoassay (ELISA), PAI-1 activity by a parabolic-rate chromogenic assay, and lupus anticoagulant (LA) activity by a standard mixing test. For t-PA and PAI-1, measurements were made on morning and evening plasma samples. The two groups of patients did not differ significantly with respect to age, sex, plasma lipids or anti-inflammatory drugs. Most APS patients (7/9) but none of the controls were taking warfarin. Between the APS and the control patients no significant differences were detected in t-PA, PAI-1, vWF or AECA levels. When APS patients were considered alone, vWF levels correlated positively with IgG ACA levels (r = 0.81, P < 0.01) and negatively with platelet count (r = -0.68, P < 0.05). There was no correlation between levels of ACA or LA activity and t-PA, PAI-1 or AECA. Compared with healthy volunteers, the diurnal variation of t-PA and PAI-1 was blunted in the two patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Significance of Anti-endothelial Cell Antibodies in Systemic Vasculitis: A Longitudinal Study Comparing Anti-endothelial Cell Antibodies and Anti-neutrophil Cytoplasm Antibodies

Ten patients with systemic vasculitis, all positive for anti-neutrophil cytoplasm antibody (ANCA), were followed for a mean of 36 weeks to determine the prevalence of anti-endothelial cell antibodies (AECAs) and the relationship between AECAs, ANCAs, and disease activity. Anti-endothelial cell antibodies were detected in eight (80%) patients at some time during the study. The levels of both AECAs and ANCAs changed with time, and these autoantibodies were present in 48% and 63% of the total 100 serum samples, respectively. Eighteen clinical remissions were observed; in 16 (88.9%) cases the level of ANCAs dropped. Fifteen (83.3%) of the 18 remissions were among the AECA-positive patients and the level of AECAs decreased in 13 (86.7%) instances (P = not significant). There were 11 episodes of disease relapse; all were associated with an increase in the level of ANCAs. Nine (81.8%) of the 11 relapses were among AECA-positive patients, and the level of AECAs increased in eight (88.9%) cases (P = not significant). Serum levels of AECAs appeared less suppressible by cyclophosphamide therapy compared with ANCAs, and patients who were persistently positive for AECAs despite being ANCA-negative during remissions were at risk of subsequent relapse. Disease recrudescense was not observed in patients persistently tested negative for both AECAs and ANCAs. Intravenous immunoglobulin therapy was used in four patients and resulted in clinical improvement in all cases, but with variable changes in the levels of AECAs and ANCAs. We conclude that AECAs are commonly detected in patients with systemic vasculitis and their levels show a relationship to disease activity similar to that for ANCAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating intercellular adhesion molecules-1 and autoantibodies including anti-endothelial cell, anti-cardiolipin, and anti-neutrophil cytoplasma antibodies in patients with vasculitis

Circulating intercellular adhesion molecule-1 (ICAM-1) and 3 types of autoantibodies were measured in 30 patients with angiographical or pathological proved vasculitis. There were 18 patients with systemic vasculitis and 12 patients with cutaneous vasculitis. The measured antibodies included anti-endothelial cell antibodies (AECA), anti-cardiolipin (ACL) antibodies of 3 isotypes and anti-neutrophil cytoplasma antibodies (ANCA). The results showed that patients with systemic vasculitis had elevated levels of ICAM-1, AECA and IgG isotype antibody as compared with none or lower in patients with cutaneous vasculitis. Levels of ICAM-1 and IgG isotype ACL antibodies also decreased significantly after disease activity subsided in patients with systemic vasculitis. Measurement of ICAM-1 and autoantibodies may be useful in evaluating the extent of involvement and in following the disease activity of patients with vasculitis.

Hypothyroidism and anti‐endothelial cell antibodies

Because of our previous demonstration of anti-endothelial cell antibodies (AECA) in patients with insulin-dependent diabetes mellitus and their association, in this condition, with thyroid disease, we sought these antibodies in patients with suspected thyroid dysfunction using an enzyme immunoassay with human umbilical vein endothelial cells as the substrate. AECA were found in 5/120 (4.2%) patients with normal and 15/97 (15.4%) with abnormal thyroid function. The increased prevalence in the latter group was due to a highly significant association between the presence of AECA and raised levels of TSH. We conclude that a highly significant correlation exists between the levels of AECA and TSH, but not between those of AECA and fT4. Patients with hypothyroidism as defined by high levels of TSH have AECA significantly more often than patients with low or normal TSH (22.2% versus 2.8% and 5.8%).

Anti-endothelial cell antibodies: detection and characterization using a cellular enzyme-linked immunosorbent assay.

Anti-endothelial cell antibodies (AECA) have been detected in autoimmune diseases such as systemic lupus erythematosus (SLE) and scleroderma (PSS) but their role in pathogenesis is unknown. Immunofluorescence, immunohistochemistry, complement-dependent antibody lysis, and radioimmunoassay have been used in the past to detect AECA. We have developed a rapid, sensitive, and quantitative cellular enzyme-linked immunosorbent assay (ELISA) to detect and characterize AECA. Sera were obtained from 28 normal volunteers, 28 patients with SLE, and 14 patients with PSS. We also performed studies in 47 patients with various monoclonal gammopathies. Endothelial cells (EC) were obtained from human umbilical veins by standard methods and subcultured on 96-well tissue culture plates without fixation. EC were then sequentially incubated with sera, peroxidase-conjugated goat anti-human Ig (IgG, IgM, or IgA), and substrate. Optical density readings were converted to arbitrary units by developing a standard curve. Heavy-chain specific antibodies were used to determine the class of AECA binding to EC. IgG was purified by using protein A columns and digested with pepsin to obtain F(ab')2 fragments. The mean units of AECA from normals were 19.3 for IgG and 12.5 for IgM. SLE sera showed significant levels of IgM AECA (37 units, P less than 0.001) but not IgG (29 units, P less than 0.1). PSS sera showed significant levels of both IgM AECA (38 units, P = 0.001) and IgG AECA (42.7 units, P less than 0.005). IgA AECA were not detected in normal, SLE, or PSS sera. Blocking Fc receptors with rabbit IgG did not affect the titer of IgG or IgM AECA.(ABSTRACT TRUNCATED AT 250 WORDS)