Increased adhesion of polymorphonuclear leukocytes to vascular endothelium by specific interaction of endogenous (interleukin-1) and exogenous (lipopolysaccharide) substances with endothelial cells 'in vitro'.

Cultured human endothelial cells exposed to interleukin-1 (IL-1) exhibited increased adhesiveness for human polymorphonuclear leukocytes (PMNs). This phenomenon was dose-dependent, maximal increased adhesion being observed at 0.25 U/ml IL-1. ECs required a minimum exposure time of 30 min. with IL-1 followed by at least 1-2 hours incubation for expression of increased adhesiveness. Incubation for shorter periods of time did not induce significant changes in EC-PMN adhesion compared with cultures having received no IL-1. No change in adhesion was observed when IL-1 was co-incubated with ECs and PMNs. Similar results were observed using lipopolysaccharide (LPS) as stimulus. It is concluded that increased adhesion of PMNs to vascular endothelium is mediated by the direct interaction of endogenous (IL-1) and exogenous (LPS) substances with ECs, the expression of which requires a latent period of 1-2 hours and is protein synthesis-dependent. The implications of these novel findings in pathological disease states are discussed.