Adherence of human leukocytes to synthetic polymeric surfaces

Synthetic polymers used in extracorporeal circulatory devices promote or exacerbate inflammatory responses. We have developed a sensitive reproducible centrifugation assay to measure adherence of 111indium-oxine labelled leukocytes to synthetic membranes; the effects of various conditions such as duration of incubation, the presence of chemotactic factor or presence of protein on the extent and strength of attachment of human leukocytes to artificial membranes were studied. Adherence of leukocytes to the membranes was found to be time dependent, especially during the initial stage of incubation. The presence of plasma in the medium, or a plasma protein-precoated surface, markedly inhibited adhesion of leukocytes. The number of leukocytes adhering to protein-treated surfaces was ten times lower than for untreated surfaces. All tested membranes, Polypropylene 2402, Supor 200 Hiflow, Cuprophan 100 PM and The True Membrane reacted in similar way with the exception being the Tuffryn HT-650 membrane. Titration with leukocytes indicated that cells incubated in PBS adhered as a monolayer, whereas cells incubated in plasma did not. The percentage of leukocytes adhering to the polypropylene membranes was reduced in a concentration-dependent fashion by chemotactic peptide fMLP.