Anti-endothelial cell antibodies in patients with various forms of vasculitis

To determine the prevalence of anti-endothelial cell antibodies (AECA) in various forms of vasculitis and to evaluate their relationships with markers of endothelial cell (EC) injury such as thrombomodulin (TM), von Willebrand factor antigen (vWf) and protein S.

A total of 167 disease-associated sera, from 79 patients with large- or medium-sized (group I) and 88 with small-sized vessel vasculitis (group II), were examined for the presence of AECA using a cellular enzyme-linked immunosorbent assay (ELISA). These were evaluated before and after incubation with epithelial cells. EC plus epithelial cell (eC) extracts were fractionated and blotted with selected sera, and EC plus mononuclear cell extracts were dotted and blotted with lupus sera. Soluble TM, vWf and protein S levels were measured by ELISA.

The binding of antibodies to eC was significant in group II sera (p < 0.01) but not in group I sera, so that the remaining EC-specific activity was significantly higher (p < 0.001) in the latter group than in the former. Eight antigenic specificities appeared to be specific for EC, whereas three were shared with eC. Despite absorption, the sera remained as reactive with EC and MNC as before. Taking the patient group as a whole, the levels of serum TM correlated with the titers of IgG, IgM and IgA AECA.

EC-specific activity is more often encountered in group I than in group II patients. At present, the explanation for the distinct AECA specificities in these disease associated sera is not clear.