Anti-endothelial cell antibodies (AECA) in systemic sclerosis - Increased sensitivity using different endothelial cell substrates and association with other autoantibodies

Objective: One of the main features of systemic sclerosis (SSc) is vascular damage, the mechanism of which is not understood. In-the present study we examined whether screening of SSc patients for different anti-endothelial c ells antibodies (AECA) of various origins increase the sensitivity of AECA detection in SSc patients. Secondary aim was an attempt to correlate AECA w ith other common autoantibodies. Materials & methods: 478 SSc patients were studied for the presence AECA, a nti-cardiolipin (aCL), anti-dsDNA, anti-heparin (AHA), anti-pyruvate dehydr ogenase (PDH) and anti-PDC-E2 autoantibodies. AECA levels were determined u sing human umbilical vein EC (HUVEC), bone marrow EC (BMEC), EC hybridoma ( EA.hy 926) and Kaposi sarcoma EC (KS). Results: Positive AECA were found in 49.5% of SSc patients (27.1% HUVEC; 34 .3% BMEC; 26.3% EaHy 926 and 22.7% KS). The highest percent reactivity of A ECA was obtained using microvascular BMEC. When combining BMEC and either o ther cell lines the reactivity ranged from 41.4% to 46%. A significant asso ciation between AECA on the one hand and AHA (p<0.001) and anti-PDH (p<0.05 ) on the other was seen. Cross-reactivity with anti-PDC-E2 was excluded by inhibition tests, but AHA and anti-PDH may be part of the spectrum of AECA. Conclusions: Since false-negative AECA may result from lack of expression o f various antigens on a specific EC, analysis of AECA in SSc patients requi res using several EC types, including microvascular EC.