Patients with SLE have increased numbers of circulating apoptotic endothelial cells that correlate with disease activity. (A) Number of circulating CD146⁺ cells expressing annexin V (CD146^AnnV) per volume of blood (milliliter) in healthy control subjects and in patients with SLE and CAD. (*P < .01, results represent mean ± SD). (B) Dot-plots displaying circulating apoptotic ECs in a healthy control subject, and 3 patients with SLE with different degrees of disease activity, as measured by SLEDAI. On the basis of the PBMC counts, we calculated the absolute number of circulating CD146^AnnV+ per milliliter, represented in the right upper quadrant.