Inhibition of cell adhesion molecule expression by ritonavir.

Flow cytometry (FACS) histograms of adhesion molecule expression were obtained from endothelial cells (HUVECs) that were treated in cultures (about 80% confluent) with TNF-α (5 ng/mL) or with TNF-α and ritonavir (20 μmol/L) for 4 hours. Aliquots of detached cells were stained with PE-conjugated antibodies for VCAM-1 (A), ICAM-1 (B), and E-selectin (C), as well as isotype-matched controls. Expression of adhesion molecules on TNF-α– and ritonavir-treated cells (solid line) was compared with TNF-α–stimulated cells (dotted line) and untreated cells (dashed line) as depicted in histogram overlays. Two independent experiments with similar results were performed.