Antiendothelial cell antibodies: useful markers of systemic sclerosis.

BACKGROUND: Systemic sclerosis (SS) encompasses a wide spectrum of clinical presentations. Antiendothelial cell antibodies (AECA) in patients with primary Raynaud's phenomenon (PRP), limited SS (lSSc), or diffuse SS (dSSc) may help to determine the long-term prognosis of the disease. METHODS: Twenty-seven normal controls, 13 patients with PRP, 36 with lSSc, and 31 with dSSc were included in the study. Sera were examined for the presence of AECA, using a cellular enzyme-linked immunosorbent assay (ELISA). Angiotensin-converting enzyme (ACE) activity, plasma von Willebrand factor antigen (vWfAg), and thrombomodulin (Tm) concentrations were also evaluated. The medical records of 50 of the lSSc and dSSc patients were reviewed and the organ system involvement noted. RESULTS: Antiendothelial cell antibodies were present in 3 patients with PRP, 16 patients with lSSc, and 26 patients with dSSc. These autoantibodies were mainly of the IgG isotype. There was no difference in ACE activity between patients and controls. In contrast, vWfAg and Tm concentrations were higher in patients with PRP relative to controls, and higher in patients with lSSc compared with those with PRP. The presence of AECA was associated with digital scars and ulcers (P < 0.004 and P < 0.003, respectively), severe RP (P < 0.01), grade 3 tortuosity of vessels (P < 0.0004), and lung involvement (P < 0.02). CONCLUSION: The significant trend for AECA to increase with disease severity across the three groups of patients studies suggests that the AECA test can identify subsets of SSc with differing prognoses.

Establishment and characterization of permanent human endothelial cell clones.

Though vasculitic diseases have been claimed to be associated with anti-endothelial cells antibodies (AECA), there is a widespread awareness of the limitations of the tests currently in use. Our objective was therefore to establish clones, in the hope that some of them would express disease-specific membrane autoantigens. Two EC lines and 7 clones were established by fusing human umbilical vein EC with epithelial A549/8 cells, and cloning by limiting dilution. An additional clone was derived from the EA.hy 926 cell line. All clones carried EC markers, such as thrombomoduline (TM) and platelet-EC adhesion molecule 1 but differed from each other, depending on whether they expressed HLA class II antigen, LFA-1, thrombospondin receptor or von Willebrand factor (vWf) antigen. Clones were also characterized by their ability to release tissue plasminogen activator, interleukin 6, TM and vWf. This panel is meant to distinguish reactivities of AECA.

Anti-endothelial cell antibodies in patients with various forms of vasculitis.

OBJECTIVE: To determine the prevalence of anti-endothelial cell antibodies (AECA) in various forms of vasculitis and to evaluate their relationships with markers of endothelial cell (EC) injury such as thrombomodulin (TM), von Willebrand factor antigen (vWf) and protein S. METHODS: A total of 167 disease-associated sera, from 79 patients with large- or medium-sized (group I) and 88 with small-sized vessel vasculitis (group II), were examined for the presence of AECA using a cellular enzyme-linked immunosorbent assay (ELISA). These were evaluated before and after incubation with epithelial cells. EC plus epithelial cell (eC) extracts were fractionated and blotted with selected sera, and EC plus mononuclear cell extracts were dotted and blotted with lupus sera. Soluble TM, vWf and protein S levels were measured by ELISA. RESULTS: The binding of antibodies to eC was significant in group II sera (p < 0.01) but not in group I sera, so that the remaining EC-specific activity was significantly higher (p < 0.001) in the latter group than in the former. Eight antigenic specificities appeared to be specific for EC, whereas three were shared with eC. Despite absorption, the sera remained as reactive with EC and MNC as before. Taking the patient group as a whole, the levels of serum TM correlated with the titers of IgG, IgM and IgA AECA. CONCLUSION: EC-specific activity is more often encountered in group I than in group II patients. At present, the explanation for the distinct AECA specificities in these disease associated sera is not clear.

Role of beta 2-glycoprotein I in the anticardiolipin antibody affinity for phospholipid in autoimmune disease.

The binding capacity to cardiolipin and the functional affinity of affinity-purified anticardiolipin (aCL) IgG of patients with autoimmune disease have been compared with those of individuals with malaria and acquired immunodeficiency syndrome (AIDS). The binding of autoimmune IgG aCL was enhanced gradually by the incorporation of increasing amounts of beta 2-glycoprotein I (beta 2GPI) into the assay, in contrast to that of patients with infectious diseases. In addition, there were significant reductions of functional affinity in autoimmune disease, but not in malaria or in AIDS. These results indicate that beta 2GPI requirement for binding to the target antigen varies inversely with functional affinity in autoimmune disease when beta 2GPI was present, and suggest that IgG aCL are more heterogeneous in this type of disorder than in patients with infectious disease.

Prevalence of anti-endothelial cell antibodies in patients with Sneddon's syndrome.

BACKGROUND: Sneddon's syndrome consists of widespread livedo reticularis and ischemic cerebral manifestations. Its pathogenesis remains unclear. Endothelial cells could be the primary target tissue. OBJECTIVE: Our aim was to determine the prevalence of anti-endothelial cell antibodies (AECA) in a large series of patients with Sneddon's syndrome. The results were compared with those of three groups of control subjects: 39 patients with active periarteritis nodosa, 20 patients hospitalized for stroke without livedo, and 28 healthy persons. METHODS: AECA were detected with enzyme-linked immunosorbent assay with hybrid cells (EA.hy926) before and after absorption on epithelial cells (A 549/8) to avoid false positivity from antibodies reacting with membranous epithelial antigens. RESULTS: Twenty-two patients with Sneddon's syndrome had AECA (35%). Of the control subjects, 11 patients with active periarteritis nodosa (28%), 1 of 20 patients with a recent stroke without livedo, and no healthy persons had AECA. CONCLUSION: AECA were frequently found in patients with Sneddon's syndrome, in contrast to the patients with stroke without livedo. The clinical significance and involvement of these antibodies in the pathogenesis of endothelial lesions in Sneddon's syndrome remain to be ascertained.

Role of beta 2-glycoprotein I in the antiphospholipid antibody binding to endothelial cells.

A group of anticardiolipin antibodies (aCL) require beta 2-glycoprotein I (beta 2GPI) to recognize their target, which might be located on endothelial cells (EC) and/or platelets. Following incubation with epithelial cells, 13 of 30 lupus sera retained EC-reactive antibodies of the IgG, IgA and IgM isotypes. Associated aCL and anti-phosphatidylethanolamine antibodies were partly absorbed on eC as well as EC. The former antibodies were more efficiently removed in the presence than in the absence of the latter. The presence of beta 2GPI in the affinity-purified aCL preparations may explain their binding to EC, as this cross-reaction was abrogated by the removal of the cofactor and restored by its re-introduction. Seventy four per cent of EC were faintly stained with polyclonal or monoclonal antibody directed to the cofactor. The beta 2GPI mediated aCL binding to EC membranes could this be influential in the development of thrombosis and/or thrombocytopenia in aCL-positive patients.

The relationship of anti-endothelial cell antibodies to anti-phospholipid antibodies in patients with giant cell arteritis and/or polymyalgia rheumatica.

Sera from patients with giant cell arteritis and/or polymyalgia rheumatica were tested for the presence of IgG, IgM and IgA antibody to endothelial cells (AEC), cardiolipin (ACL) and phosphatidylethanolamine (APE) using enzyme-linked immunosorbent assays. There were strong correlations between ACL and APE, but also between AEC and ACL IgM (p < 0.02) and between AEC and APE IgA (p < 0.003). Inhibition of AEC binding was achieved by absorption onto EC, but ACL and APE binding was also significantly reduced. In contrast, the binding of AEC antibody could not be inhibited by incubation with CL. Our data suggest that AEC constitute a heterogeneous population of autoantibodies.

Anti-endothelial cell antibodies: a need for standardization.

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.

[Anti-endothelial cell antibodies in vasculitis in general, Sneddon's syndrome in particular]. / Anticorps anti-cellules endothéliales dans les vascularites en général, le syndrome de Sneddon en particulier.

Stringent conditions have been applied to set up an "enzyme-linked immunosorbent assay" to detect anti-endothelial cell autoantibodies. These predominated in Sneddon's syndrome.