Clinical associations of anti-endothelial cell antibodies in patients with systemic lupus erythematosus

The aim of this study was to define the clinical associations of anti-endothelial cell antibody (AECA) in systemic lupus erythematosus (SLE) patients by measuring serum AECA titers to correlate with the disease activity and clinical manifestations. Forty-one SLE patients and 27 controls were studied. Serum samples were collected at the time of patient presentation with disease exacerbation and 4 weeks after the start of treatment. The disease activity was evaluated by the SLE Disease Activity Index (SLEDAI). AECA was detected by enzyme-linked immunosorbent assay (ELISA) methods with the surface antigen of the immortalized human microvascular endothelial cell line (HMEC-1). The mean immunoglobulin (Ig)G-AECA and IgM-AECA optical densities (ODs) were significantly higher in patients with SLE compared with controls [mean ± standard deviation (SD), 0.32 ± 0.15 vs 0.18 ± 0.16 and 0.29 ± 0.14 vs 0.21 ± 0.09, respectively]. There was a positive correlation between IgG-AECA and the SLEDAI scores. The positivity rate of AECA in the groups with digital vasculitis, neuropsychiatric lupus, and anti-cardiolipin antibody was significant. In conclusion, AECA may be involved in the pathogenesis of SLE and was correlated with the disease activity. It was also associated with clinical manifestations such as digital vasculitis, neuropsychiatric lupus, and anti-cardiolipin antibody positivity.