Cell-to-cell contact between sickle mononuclear leukocytes and HUVEC enhances, but is not required for, up-regulation of adhesion molecules and tissue factor.

To prevent cell-to-cell contact, mononuclear leukocytes and endothelial cells (1.5 mononuclear leukocyte/endothelial cell) were separated by cell culture inserts with 0.4-μm, high-pore density membranes during the 4-hour incubation. HUVEC E-selectin, ICAM-1, VCAM-1, and tissue factor were measured by enzyme immunoassay, and the results are expressed as a percentage of control (media only)-treated HUVEC (100%). Results are from a single representative experiment of 2.