Effects of surface modification of materials on human neutrophil activation

The properties of a polymer surface affect the cellular functions and morphology of cells in contact with the polymer. In this paper, we will demonstrate the effects of surface modification of materials on various neutrophil markers of activation. The sulfonation of a polystyrene surface caused increases in its negative charge and hydrophilicity. The sulfonation did not affect the number of adhered neutrophils, but the shape of the neutrophils adhered on the material was different; a round shape on highly sulfonated polystyrene and a spread shape on weakly sulfonated or non-sulfonated polystyrene. Expression of the adhesion molecule, CD11b, on neutrophils was also affected by the properties of the polymer surface. CD11b was expressed in neutrophils adhered on polystyrene and the expression decreased with increasing sulfonation of the surface. The expression of CD11b on the neutrophils on highly sulfonated polystyrene was the same as that on non-adhered neutrophils. In contrast, the expression of CD11a was not affected by the properties of the material surface. The F-actin content of activated neutrophils and the production of active oxygen groups detected by means of luminol-dependent chemiluminescence were also dependent on the sulfo-group content of the material surface. Finally, the translocation of protein kinase C (PKC) was determined in neutrophils adhered to these materials. Compared to non-adhered cells, the ratio of membrane bound to cytosolic PKC increased in adhered cells, but the increase was suppressed by sulfonation of the material surface. These data suggest that activation of neutrophils on polystyrene is suppressed by surface modification with increasing negative charge and/or hydrophilicity.