Transendothelial chemotaxis in vitro of human monocytes

Porcine aortic vascular endothelial cells were grown to confluence on microporous PTFE membranes and incorporated into a two-compartment chemotaxis assembly. Human peripheral blood mononuclear cells (20-25% monocytes) were placed in the upper compartment and zymosan-activated human serum (ZAHS) as chemoattractant in the lower compartment. Over a 3 h period monocytes migrated across the endothelialized membrane and adhered to a collecting filter sited in the lower compartment. Addition of ZAHS to the cell suspension in the upper compartment virtually abolished the migration response whilst only minimal leucocyte migration was supported by the bare unendothelialized PTFE membrane. The extent of transendothelial monocyte chemotaxis was dependent upon the concentration of chemoattractant in the lower compartment and upon the cell density of the suspension containing monocytes. A confluency test of fluid flow across the endothelialized filter showed that monocyte migration could take place without disturbing endothelial barrier function. The culture system is easy to assemble and the method provides experimental versatility.