Anti-endothelial cell antibodies in patients with interstitial lung diseases.

BACKGROUND: Anti-endothelial cell antibodies (AECA) are circulating antibodies that bind to endothelial antigens and induce endothelial cell damage. AECA have been detected in patients with collagen vascular disease (CVD) and their presence is associated with interstitial lung disease (ILD) in cases of CVD. However, the prevalence of AECA in patients with idiopathic interstitial pneumonias (IIPs) is not known.

METHODS: We investigated the prevalence of AECA in patients with IIPs. We also examined whether the expression of AECA differed among the histologic subgroups usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP), and compared the values with those of CVD-associated ILD (CVD-ILD). Twenty patients with IIPs and 24 patients with CVD-ILD were studied. Serum samples were examined for AECA by cellular enzyme-linked immunosorbent assay (ELISA) using human umbilical vein endothelial cells. Values are expressed as ELISA ratios (ER).

RESULTS: All sera from patients with idiopathic pulmonary fibrosis (IPF)/UIP were negative for AECA, whereas 5 out of 10 with idiopathic NSIP, 5 out of 14 with CVD-UIP and 4 out of 10 with CVD-NSIP tested positive (p<0.05). ER values were significantly lower in patients with IPF/UIP than idiopathic NSIP, CVD-UIP or CVD-NSIP (p<0.05). Among idiopathic NSIP, CVD-NSIP and CVD-UIP patients, the ER values did not differ.

CONCLUSIONS: Among IIP patients, only those with idiopathic NSIP, not IPF/UIP, tested positive for AECA. The prevalence of AECA in idiopathic NSIP patients was similar to that in CVD-ILD patients. These results may provide important information to understand the distinct pathophysiology of each form of IIPs.