Quantitative studies of human monokine-induced endothelial cell elongation

Leucocyte-endothelial cell interactions are important in the inflammatory response. In this study, the effect of peripheral blood mononuclear cell (PBMC) products on endothelial cell (EC) shape was examined and quantified. PBMC were obtained from normal donors by Ficoll-Hypaque separation of heparinized whole blood and cultured for 72 hr in media containing 10% fetal calf serum with and without concanavalin A (Con A). Media conditioned by PBMC or control, nonconditioned media were then added to preconfluent, first passage EC cultures derived from human umbilical veins. Conditioned media from Con A-stimulated PBMC resulted in a dose-dependent, marked elongation and whorling of cultured EC. The minimum effective concentration found to elicit a response was 1.25%, with a maximum response occurring at 10%. Quantitative morphometric analyses of treated EC indicated that the elongation was highly significant (p less than 0.001) when compared to EC incubated with control, nonconditioned media. In addition, EC elongation was accompanied by a highly significant (p less than 0.001) increase in cell area. Although less dramatic, conditioned media from unstimulated PBMC also elicited a similar, significant dose-dependent change in EC shape. Significant changes in EC shape were evident within 6 hr and continued over the time course of the experiment (40 h). Cell shape changes were partially reversible at 18 h after removal of the PBMC-conditioned media and replacement with control, nonconditioned media. The change in EC morphology induced by a PBMC-derived factor(s) suggests a mechanism by which activated leucocytes may modulate cellular traffic at the blood-vessel wall interface.