Objective: To assess the frequency of antiendothelial cell autoantibodies (AECAs) in a group of patients with systemic sclerosis (SSc) and possible associations with clinical and serologic features of the disease.
Methods: Sera from 50 patients with SSc (38 with the limited and 12 with the diffuse form) were screened for AECA (ELISA). The reference limits were were 56.6% for the IgM isotype and 3.3.5% for the IgG isotype. AECA results were analyzed in relation to lung involvement (chest x-ray, high resolution computed tomography (HRCT), ventilation scintiscan with radioaereosol (DTPA), pulmonary pressure (echodoppler technique): heart involvement (EKG, 24 hr ambulatory EKG, echocardiography), cutaneous involvement (skin score), capillaroscopic characteristics and digital ulcers. AECA were also correlated with the erythrocyte sedimentation rate (ESR), anticentromere (ACA) and antitopoisomerase I (ATA) autoantibodies, and angiotensin converting enzyme plasma levels (ACE).
Results: The AECA IgG prevalence was 40% (22/50) for the SSc group as a whole, without significant differences between subsets. A significant negative correlation was shown between the AECA and ACE plasma levels in both subsets. In the diffuse form, a significant positive correlation was found between AECA and ESR and significant associations were found between AECA and the parameters reflecting alveolo-capillary involvement (DLco, DTPA), the pulmonary artery pressures, digital ulcers and capillaroscopic abnormalities. No statistically significant correlations were found between AECA and heart involvement, the skin score or pulmonary interstitial fibrosis.
Conclusions: These data suggest that in SSc the anti-endothelial cell antibodies are directly linked to vascular injury and could reflect endothelial damage. Further studies are needed to verify whether AECA might identify a subgroup of patients at higher risk for the development of vascular crises and whether they might therefore be considered a predictor of outcome in SSc patients.