['To investigate the effect of 17beta-estradiol (E2) on binding of monocytes to human aortic endothelial cells (HAECs) with or without cytokine induction.', 'Confluent monolayers of HAECs were incubated with or without E2 for 48 h prior to the monocyte adhesion assay. In studies with cytokines, 1 ng/ml tumor necrosis factor-alpha (TNF-alpha), 20 U/ml interleukin-1beta (IL-1beta) or both were added to the culture medium for the final 24 or 4 h. For the measurement of monocyte adhesion, 3H-thymidine labeled human THP-1 monocytes (4 x 10(5) cells per well) were added to the confluent monolayer of HAECs and incubated at 37 degrees C for 90 min. The unbound THP-1 cells were removed by gentle washing, and bound cells were digested with NaOH and quantified by measuring radioactivity.', 'When HAECs were pretreated for 48 h with E2 the basal adhesion of THP-1 cells was reduced by an average of 28%. Estrogen significantly reduced cytokine-induced adhesion by 30-35% when the cytokines were added for 4 h. When the cytokine treatment was prolonged to 24 h, pretreatment of HAECs with E2 had no effect on THP-1 cell adhesion.'] Does estradiol reduce basal and cytokine induced monocyte adhesion to endothelial cells?