HUMAN MONOCYTE-MACROPHAGE ADHESION AND CYTOKINE PRODUCTION ON SURFACE-MODIFIED POLY(TETRAFLUOROETHYLENE HEXAFLUOROPROPYLENE) POLYMERS WITH AND WITHOUT PROTEIN PREADSORPTION

To study surface property-dependent human monocyte adhesion and cytoki ne (IL-1 beta, IL-6, TNF-alpha) production, poly(tetrafluoroethylene/h exafluoropropylene) (FEP) polymer was modified to exhibit neutral, ani onic, or cationic properties by incorporating amide (CONH2) and/or car boxyl (COOH) or aminoethyl amide [CONH(CH2CH2NH)(n)CH2CH2NH2] groups o n the surface. Monocyte adhesion on surface-modified FEP polymers and cytokines released by monocytes/macrophages (MC/MO) into the culture m edium were compared to control tissue culture polystyrene (TCPS) at da ys 1 and 8. On day 1, the neutral surface FEP polymer with incorporate d amide (NH2) groups showed the greatest inhibition of adhesion, 89% ( P < .01), and cytokine production (IL-1 beta with 58%, IL-6 with 70%, and TNF-alpha with 39%) compared to control TCPS. In contrast, the hig hly cationic [CONH(CH2CH2NH)(n)CH2CH2NH2] surface did not show signifi cant (P > .01) inhibition of monocyte adhesion and cytokine production . When fibrinogen or IgG was preadsorbed to the surface, the inhibitor y effects of the neutral surface FEP polymer on monocyte adhesion and cytokine production were not altered. In addition, other surface-modif ied FEP polymers showed similar inhibition of monocyte adhesion and cy tokine production compared to TCPS. Specifically, as the incorporation of carboxyl (COOH) group content increased on FEP polymer surfaces, m onocyte adhesion and cytokine production were also increased on day 1 with IgG preadsorption. On day 8, all surface-modified FEP polymers sh owed significant (P < .01) inhibition of monocyte adhesion when fibrin ogen or IgG was preadsorbed. However, without protein (fibrinogen or I gG) preadsorption, monocyte adhesion was not significantly inhibited c ompared to control TCPS. In addition, cytokine production detected by ELISAs on day 8 showed no detectable levels of IL-1 beta and significa ntly decreased levels of IL-6 compared to day 1 for all tested polymer s, with or without protein preadsorption. Interestingly, the level of TNF-alpha production on day 8 remained high although not as high as on day 1. Based on these results, we suggest that FEP polymers with neut ral hydrophilic surface properties may adhere and activate the least n umber of monocytes, which are important mediators of biocompatibility. (C) 1995 John Wiley and Sons, Inc.