An SV40 large T-antigen immortalized human umbilical vein endothelial cell line for anti-endothelial cell antibody detection.

OBJECTIVE: Anti-endothelial cell antibodies in serum of patients with different inflammatory diseases can be detected by a whole cell enzyme-linked immunosorbant assay, using primary cultures of human umbilical vein endothelial cells. To avoid repeated isolation, it would be of great value if an immortal endothelial cell line could be used to perform anti-endothelial cell antibody assays. METHODS: In this study endothelial cells from human umbilical and iliac veins and arteries were transfected with a plasmid containing the Simian Virus 40 large T-antigen. Endothelial cell line(s) derived from this procedure were compared with human umbilical vein endothelial cells in the anti-endothelial cell antibody assay. RESULTS: After transfection, clones of homologous cell populations showed an extended lifespan, before entering a period of crisis. In one human umbilical vein endothelial cell clone a subpopulation of cells escaped crisis and became immortal (EVLC2). Telomerase was activated in this endothelial cell line, resulting in maintenance of the telomere length. There was a significant correlation between anti-endothelial cell antibody testing on human umbilical vein endothelial cells and on the cell line EVLC2. CONCLUSION: The Simian Virus 40 large T-antigen immortalized human umbilical vein endothelial cell line EVLC2 may be useful for the detection of anti-endothelial cell antibodies.

Clinical significance of anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver diseases.

BACKGROUND/AIMS: The clinical relevance of anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver disease is unclear. Defining the antigenic specificities of ANCA in these diseases may improve their clinical significance. METHODS: We studied the target antigens of ANCA in 88 patients with autoimmune hepatitis, 53 patients with primary biliary cirrhosis, and 55 patients with primary sclerosing cholangitis by indirect immunofluorescence, antigen-specific enzyme-linked immunosorbent assays, and immunodetection on Western blot, using an extract of whole neutrophils as a substrate. We related the data to clinical symptoms of autoimmune liver disease. RESULTS: By indirect immunofluorescence, ANCA were present in 74% of patients with autoimmune hepatitis, 26% of patients with primary biliary cirrhosis, and 60% of patients with primary sclerosing cholangitis. Major antigens were catalase, alpha-enolase, and lactoferrin. The presence of ANCA as detected by indirect immunofluorescence was associated with the occurrence of relapses in autoimmune hepatitis, with decreased liver synthesis function in primary biliary cirrhosis and in primary sclerosing cholangitis, and with increased cholestasis in primary sclerosing cholangitis. ANCA of defined specificities had only limited clinical relevance. CONCLUSIONS: ANCA as detected by indirect immunofluorescence seem associated with a more severe course of autoimmune liver disease. The target antigens for ANCA in these diseases include catalase, alpha-enolase, and lactoferrin. Assessment of the antigenic specificities of ANCA in autoimmune liver disease does not significantly contribute to their clinical significance.

Staphylococcal acid phosphatase binds to endothelial cells via charge interaction; a pathogenic role in Wegener's granulomatosis?

The majority of patients with Wegener's granulomatosis (WG) are chronic nasal carriers of Staphylococcus aureus. Chronic nasal carriage of S. aureus is associated with an increased risk of developing a relapse of the disease. The mechanism by which this occurs is still unknown. We hypothesized that a cationic protein of S. aureus, staphylococcal acid phosphatase (SAcP), acts as a planted antigen and initiates glomerulonephritis and vasculitis in patients with WG. In order to test the hypothesis that SAcP can act as a planted antigen in WG, we studied the ability of SAcP to bind to human umbilical vein endothelial cells (HUVEC) and human glomerular endothelial cells. We also studied whether this binding can be prevented by preincubation with an anionic protein, and whether binding of SAcP activates endothelial cells. We also evaluated whether antibodies in sera of patients with WG are able to bind to endothelial cell-bound SAcP. The results show that SAcP can act as a planted antigen by binding to both types of endothelial cells in a concentration-dependent manner. Binding of concentrations as low as 4 microg/ml can be detected on HUVEC within 5 min of incubation. Binding of SAcP to endothelial cells was charge-dependent but did not activate endothelial cells. Finally, endothelial cell-bound SAcP was recognized by sera of patients with WG. The data suggest a possible pathogenic role for SAcP by acting as a planted antigen thereby initiating glomerulonephritis and vasculitis in patients with WG.

In vitro up-regulation of E-selectin and induction of interleukin-6 in endothelial cells by autoantibodies in Wegener's granulomatosis and microscopic polyangiitis.

OBJECTIVE: In patients with Wegener's granulomatosis (WG) or microscopic polyangiitis (MPA) autoantibodies to myeloid granule proteins (ANCA), particularly proteinase 3 (Pr3) and myeloperoxidase (MPO), and to endothelial cells (AECA) are frequently detected. The role of these autoantibodies in the development of vascular injury is incompletely understood. Since the expression of E-selectin and the production of interleukin 6 by endothelial cells is an early step in the sequence of events leading to vascular injury, we examined the capacity of IgG fractions from patients with WG and/or MPA to activate endothelial cells to the expression of E-selectin and the production of IL-6. We related those findings to the presence of ANCA and AECA in the IgG preparations. METHODS: Human umbilical vein endothelial cells (HUVEC) were incubated with immunoglobulin (IgG) preparations from 28 patients (17 positive for anti-Pr3, 10 for anti-MPO, and one for anti-Pr3/MPO) with active vasculitis and from 10 healthy volunteers. The final IgG concentration in the activation assay was 2 mg/ml. TNF alpha (10 ng/ml) and LPS (10 ng/ml) were used as positive controls for HUVEC activation. The extent of HUVEC activation was assessed by the measurement of E-selectin expression by flow cytometry (after 4 hours of incubation) and the production of interleukin 6 by ELISA (after 24 hours). RESULTS: We found that 11 of the 28 ANCA positive IgG samples were capable of activating endothelial cells: six samples induced IL-6 production alone, one sample upregulated E-selectin expression alone, and four samples induced both IL-6 production and E-selectin upregulation. Five of 17 anti-Pr3 positive samples (one of which was also positive for AECA) and 6 of 10 anti-MPO positive samples (all simultaneously positive for AECA) induced endothelial cell activation. AECA positive samples that induced endothelial cell activation (n = 7) had higher AECA titres than samples that did not induce endothelial cell activation (n = 6). CONCLUSION: Our data suggest that the activation of endothelial cells in patients with WG and MPA can be induced by circulating autoantibodies. Both ANCA and AECA can be responsible for this effect.

Rapid enzyme immunoassay of anti-streptokinase antibodies in human plasma.

A simple enzyme immunoassay for determination of anti-streptokinase antibodies (aSKa) in plasma is described. Commercially available reagents have been used for the assay, which is calibrated with a reference preparation of aSKa containing 100 AU/ml. The assay is specific and reproducible with a variation coefficient of 4.8%. In healthy individuals a broad range of values between 4 and 291 AU/ml was observed with a large difference between the mean and median value (55 AU/ml and 27 AU/ml, respectively). Data from a study on 21 patients with myocardial infarction treated with the streptokinase derivative antistreplase suggest that a high titre of aSKa before treatment is associated with failure of thrombolytic therapy. The assay procedure can be shortened to 0.5 h to screen patients for a high aSKa level. This assay allows a more routine assessment of aSKa in the clinic.