ADHERENCE OF HUMAN POLYMORPHONUCLEAR LEUKOCYTES TO ENDOTHELIAL MONOLAYERS - EFFECTS OF TEMPERATURE, DIVALENT-CATIONS, AND CHEMOTACTIC FACTORS ON THE STRENGTH OF ADHERENCE MEASURED WITH A NEW CENTRIFUGATION ASSAY

Abstract

Polymorphonuclear leukocytes (PMN) adhere to endothelial cells at sites of acute inflammation. To examine this phenomenon in vitro, a new assay was developed to measure adherence of PMN to cultured endothelial cells. Human PMN were labeled with 111indium-oxine and incubated in microtiter wells with monolayers of either human umbilical vein or bovine aortic endothelial cells. Following incubation, the wells were sealed, inverted and centrifuged at varying speeds. Results are expressed as the percentage of PMN added initially that remained attached to the monolayers after being subjected to dislodgment forces (i.e., relative centrifugal forces) ranging from 1 to 1200 g. Adherence of PMN to endothelial monolayers was temperature dependent, dependent on the concentration of extracellular Mg2+ (but not Ca2+), and enhanced significantly by the chemotactic peptides, N-for-Met-Leu-Phe (fMLP) and human C5a. fMLP and C5a not only increased the number of PMN that adhered to endothelial cells, but also increased the strength of adherence.