Effect of plasma proteins on human leukocyte adhesion to plastics

The effect of human plasma and isolated plasma proteins on the adhesion of mixed human leukocytes to plastic (polystyrene) surfaces, with or without Ca++ and Mg++ depletion, was investigated. Plasma proteins were found to adsorb to plastics surfaces, and the adsorptive properties of albumin were studied in detail. The results showed that almost all leukocytes adhered to plastics in protein-free buffers, but cell adhesion was hindered in buffers containing plastic proteins. Dialyzed and heat-inactivated plasma, but not serum, were shown to inhibit leukocyte adhesion more than normal plasma. EDTA, Ca ++ - Mg ++ - free buffer or EDTA-pre-incubated leukocytes caused increased inhibition of leukocyte adhesion in the presence of plasma and some plasma proteins, but not others. It was suggested that leukocyte membranes are basically sticky to plastics, but their adhesion to protein-coated plastic surfaces involves the binding of the membrane receptors to the adsorbed proteins, and not to the plastics underneath them