The competitive effects of serum proteins on cell adhesion.

Binding curves for the adsorption of plasma fibronectin, alpha-1-antitrypsin, alpha-2-macroglobulin, ceruloplasmin, transferrin and bovine serum albumin to plain and to hydroxylated polystyrene surfaces were measured. These curves were correlated with the adhesion of BHK cells and leucocytes to these adsorbed protein surfaces in protein-free culture media. Hydroxylated polystyrene adsorbed less of alpha-1-antitrypsin, alpha-2-macroglobulin and albumin than the plain polystyrene. On the other hand the hydroxylated surfaces bound more fibronectin than the plain polystyrene surfaces. Hydroxylated polystyrene surfaces were also more adhesive for both BHK cells and leucocytes than plain polystyrene: a result confirming earlier work. The competition of fibronectin for adsorption to plain polystyrene with alpha-1-antitrypsin, alpha-2-macroglobulin and ceruloplasmin was measured and correlated with effects on cell adhesion. The results suggest that the low adhesiveness of BHK cells and leucocytes on plain polystyrene in sera-containing media is due both to the low binding of fibronectin and to the binding of serum albumin, alpha-1-antitrypsin and alpha-2-macroglobulin. The relative unimportance of fibronectin in adhesion to these surfaces is shown by the finding that cell attachment will not occur to polystyrene surfaces that have bound high levels of the antiadhesive proteins in the presence of fibronectin, even though attachment will occur in the absence of fibronectin provided that the antiadhesive proteins are lacking.