Serological distribution of anti-endothelial cell antibodies and their association with laboratory indicators in autoimmune and immune-mediated diseases.

Background: Anti-endothelial cell antibodies (AECA) are implicated in vascular injury associated with autoimmune and inflammatory diseases. However, their distribution and clinical significance across diverse conditions remain inadequately characterized.

Methods: We analyzed 1,334 serum samples from patients with vasculitis, systemic autoimmune diseases, kidney diseases, arthritis, and other immune-mediated disorders. AECA titers were measured using indirect immunofluorescence assays and categorized as low (1:100), moderate (1:320) or high (1:1000). Laboratory parameters, including hematological, renal, hepatic, and coagulation indicators, were compared among different AECA titer groups within each disease category.

Results: AECA positivity was most frequently observed in vasculitis (40.6%), arthritis (44.4%), and autoimmune kidney diseases (25.5%). Higher titers were especially common in Behet's disease, ANCA-associated vasculitis, and ankylosing spondylitis. In autoimmune nephropathy, patients with moderate to high AECA titers (≥ 1:320) exhibited significantly elevated serum creatinine and urea levels compared to both AECA-negative and low-titer groups, suggesting impaired renal function. In the kidney disease subgroup, higher AECA titers indicated lower red blood cell counts and decreased estimated glomerular filtration rate (eGFR). Among systemic autoimmune diseases, moderate to high AECA titers were linked to significantly reduced white blood cell counts.

Conclusion: AECAs show heterogeneous distribution across immune-mediated diseases and are linked to laboratory abnormalities inidicative of endothelial injury and organ dysfunction. These findings support the potential role of AECA titier as biomarkers for systemic involvement, warranting validation in prospective studies. Key Points • Anti-endothelial cell antibodies (AECAs) are heterogeneously distributed across a broad spectrum of immune-mediated diseases. • AECA positivity is associated with disease-specific patterns, particularly in Behçet's disease and ANCA-associated vasculitis. • AECA may serve as potential serological biomarkers for disease severity and immune-mediated endothelial injury.