Circulating Endothelial Cells in Vasculitis and Transplantation

Damage to microvascular endothelial cells is the hallmark of small-vessel vasculitis. Based on the histology, however, an intriguing question has long been unanswered: Given that cells undergo detachment from the basement, what happens to these cells and can we detect them in peripheral blood? Moreover, it seemed reasonable to assume that the number of circulating endothelial cells would reflect disease extent and activity. For this reason, we became interested in circulating endothelial cells as a possible marker of disease activity in ANCA-associated vasculitis. In our study [1], high numbers of cells (>100/ml) were detected in patients with active systemic vasculitis; cell numbers declined progressively during the course of successful immunosuppressive treatment. Moderately elevated numbers of circulating endothelial cells were detected in blood obtained from patients in remission. Finally, controls with infection and non-vasculitic renal disease did not have elevated cell numbers. Therefore, the positive predictive value of a cell count above 25 cells/ml was 100% while the nega