FURTHER CHARACTERIZATION OF ANTIENDOTHELIAL CELL ANTIBODIES IN SYSTEMIC LUPUS-ERYTHEMATOSUS BY CONTROLLED IMMUNOBLOTTING

Anti-endothelial cell antibodies in systemic lupus erythematosus were further characterized by controlled immunoblotting studies with EN4 de fined membrane and cytosol preparations of human umbilical vein endoth elial cells. Antibodies to endothelial cell membranes: some of which r eacted with the membranes of both dermal fibroblasts and T-cell lympho ma HUT78, were detected in 26/33 patients (78%), but in only 4/34 norm al controls (P < 0.001) and 3/11 patients with a recent myocardial inf arction. Although the antibody response was very heterogeneous against epitopes ranging from 17 to 205 kDa, there was a tendency to detect p articular membrane epitopes at 31-33 kDa (15 cases), 72-78 kDa (eight cases), 66-68 kDa (seven cases) and 17-19 kDa (five cases). No correla tions between antibodies to particular epitopes and disease manifestat ions were observed nor was a relationship to disease activity detected in a retrospective analysis. However, the possibility that anti-endot helial cell antibodies may be pathogenically important was supported b y prospective serial studies in two cases with nephritis who showed di minution and disappearance of anti-endothelial cell antibodies as thei r active disease was treated into remission.